Add verbose output to examples task

Initial discussion in #115.
Verbose output:

```
$ grunt examples -v
Initializing
Command-line options: --verbose

Reading "Gruntfile.js" Gruntfile...OK

Registering Gruntfile tasks.

Registering "grunt-contrib-clean" local Npm module tasks.
Reading /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-clean/package.json...OK
Parsing /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-clean/package.json...OK
Loading "clean.js" tasks...OK
+ clean

Registering "grunt-contrib-concat" local Npm module tasks.
Reading /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-concat/package.json...OK
Parsing /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-concat/package.json...OK
Loading "concat.js" tasks...OK
+ concat

Registering "grunt-contrib-connect" local Npm module tasks.
Reading /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-connect/package.json...OK
Parsing /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-connect/package.json...OK
Loading "connect.js" tasks...OK
+ connect

Registering "grunt-contrib-copy" local Npm module tasks.
Reading /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-copy/package.json...OK
Parsing /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-copy/package.json...OK
Loading "copy.js" tasks...OK
+ copy

Registering "grunt-contrib-uglify" local Npm module tasks.
Reading /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-uglify/package.json...OK
Parsing /Users/florent/Development/perso/phaser/node_modules/grunt-contrib-uglify/package.json...OK
Loading "uglify.js" tasks...OK
+ uglify

Registering "./tasks" tasks.
Loading "examples.js" tasks...OK
+ examples
Loading "umd.js" tasks...OK
+ umd
Reading package.json...OK
Parsing package.json...OK
Initializing config...OK
Loading "Gruntfile.js" tasks...OK
+ build, default

Running tasks: examples

Running "examples" task

Running "examples:all" (examples) task
Verifying property examples.all exists in config...OK
Files: examples/_site/js/jquery-2.0.3.min.js, examples/_site/js/phaser-examples.js, examples/_site/js/phaser-sideview.js, examples/_site/js/phaser-viewer.js, examples/_site/js/prettify.js, examples/_site/js/purl.js, examples/_site/js/run_prettify.js, examples/animation/change texture on click.js, examples/animation/local json object.js, examples/animation/looped animation.js, examples/animation/multiple anims.js, examples/animation/sprite sheet.js, examples/animation/texture packer json hash.js, examples/audio/loop.js, examples/audio/pause and resume.js, examples/audio/play music.js, examples/basics/01 - load an image.js, examples/buttons/action on click.js, examples/buttons/changing the frames.js, examples/buttons/rotated buttons.js, examples/camera/basic follow.js, examples/camera/camera cull.js, examples/camera/follow styles.js, examples/camera/moving the camera.js, examples/camera/world sprite.js, examples/collision/bounding box.js, examples/collision/group vs group.js, examples/collision/larger bounding box.js, examples/collision/offset bounding box.js, examples/collision/sprite tiles.js, examples/collision/sprite vs group.js, examples/collision/sprite vs sprite custom.js, examples/collision/sprite vs sprite.js, examples/collision/transform.js, examples/collision/vertical collision.js, examples/display/fullscreen.js, examples/display/graphics.js, examples/display/render crisp.js, examples/games/breakout.js, examples/games/invaders.js, examples/games/starstruck.js, examples/games/tanks.js, examples/geometry/circle.js, examples/geometry/line.js, examples/geometry/playing with points.js, examples/geometry/rectangle.js, examples/geometry/rotate point.js, examples/groups/add a sprite to group.js, examples/groups/bring a child to top.js, examples/groups/bring a group to top.js, examples/groups/call all.js, examples/groups/create group.js, examples/groups/create sprite in a group.js, examples/groups/display order.js, examples/groups/for each.js, examples/groups/get first.js, examples/groups/group as layer.js, examples/groups/group transform - rotate.js, examples/groups/group transform - tween.js, examples/groups/group transform.js, examples/groups/recyling.js, examples/groups/remove.js, examples/groups/replace.js, examples/groups/set All.js, examples/groups/sub groups - group length.js, examples/groups/swap children in a group.js, examples/input/cursor key movement.js, examples/input/drag several sprites.js, examples/input/drag.js, examples/input/drop limitation.js, examples/input/follow mouse.js, examples/input/game scale.js, examples/input/key.js, examples/input/keyboard hotkeys.js, examples/input/keyboard justpressed.js, examples/input/keyboard.js, examples/input/motion lock - horizontal.js, examples/input/motion lock - vertical.js, examples/input/multi touch.js, examples/input/override default controls.js, examples/input/pixel perfect click detection.js, examples/input/pixelpick - scrolling effect.js, examples/input/pixelpick - spritesheet.js, examples/input/snap on drag.js, examples/loader/pick images from cache.js, examples/misc/net.js, examples/misc/random generators.js, examples/misc/repeatable random numbers.js, examples/particles/click burst.js, examples/particles/collision.js, examples/particles/diamond burst.js, examples/particles/no rotation.js, examples/particles/random sprite.js, examples/particles/when particles collide.js, examples/particles/zero gravity.js, examples/physics/accelerate to pointer.js, examples/physics/angle between.js, examples/physics/angle to pointer.js, examples/physics/angular acceleration.js, examples/physics/angular velocity.js, examples/physics/mass velocity test.js, examples/physics/move towards object.js, examples/physics/multi angle to pointer.js, examples/physics/quadtree - collision infos.js, examples/physics/quadtree - ids.js, examples/physics/shoot the pointer.js, examples/physics/sprite bounds.js, examples/sprites/add a sprite.js, examples/sprites/add several sprites.js, examples/sprites/collide world bounds.js, examples/sprites/destroy.js, examples/sprites/dynamic crop.js, examples/sprites/extending sprite demo 1.js, examples/sprites/extending sprite demo 2.js, examples/sprites/horizontal crop.js, examples/sprites/move a sprite.js, examples/sprites/out of bounds.js, examples/sprites/scale a sprite.js, examples/sprites/shared sprite textures.js, examples/sprites/sprite rotation.js, examples/sprites/spritesheet.js, examples/sprites/vertical crop.js, examples/text/bitmap fonts.js, examples/text/hello arial.js, examples/text/kern of duty.js, examples/text/remove text.js, examples/text/text stroke.js, examples/tile sprites/animated tiling sprite.js, examples/tile sprites/tiling sprite.js, examples/tilemaps/fill tiles.js, examples/tilemaps/mapcollide.js, examples/tilemaps/mario.js, examples/tilemaps/mariotogether.js, examples/tilemaps/paint tiles.js, examples/tilemaps/randomise tiles.js, examples/tilemaps/replace tiles.js, examples/tilemaps/sci fly.js, examples/tilemaps/supermario.js, examples/tilemaps/supermario2.js, examples/tilemaps/swap tiles.js, examples/tilemaps/wip1.js, examples/tilemaps/wip2.js, examples/tilemaps/wip3.js, examples/tilemaps/wip4.js, examples/tweens/bounce.js, examples/tweens/bubbles.js, examples/tweens/chained tweens.js, examples/tweens/combined tweens.js, examples/tweens/easing spritesheets.js, examples/tweens/easing.js, examples/tweens/fading in a sprite.js, examples/tweens/pause tween.js, examples/tweens/tween several properties.js, examples/wip/body test.js, examples/wip/crop.js, examples/wip/fiddle.js, examples/wip/input active.js, examples/world/fixed to camera.js, examples/world/move around world.js -> examples/_site/examples.json

>> Destination file "examples/_site/examples.json" will be overridden.

Skipping _site/js/jquery-2.0.3.min.js...
Skipping _site/js/phaser-examples.js...
Skipping _site/js/phaser-sideview.js...
Skipping _site/js/phaser-viewer.js...
Skipping _site/js/prettify.js...
Skipping _site/js/purl.js...
Skipping _site/js/run_prettify.js...
Skipping wip/body test.js...
Skipping wip/crop.js...
Skipping wip/fiddle.js...
Skipping wip/input active.js...

Found 148 examples:
 * examples/animation/change texture on click.js
 * examples/animation/local json object.js
 * examples/animation/looped animation.js
 * examples/animation/multiple anims.js
 * examples/animation/sprite sheet.js
 * examples/animation/texture packer json hash.js
 * examples/audio/loop.js
 * examples/audio/pause and resume.js
 * examples/audio/play music.js
 * examples/basics/01 - load an image.js
 * examples/buttons/action on click.js
 * examples/buttons/changing the frames.js
 * examples/buttons/rotated buttons.js
 * examples/camera/basic follow.js
 * examples/camera/camera cull.js
 * examples/camera/follow styles.js
 * examples/camera/moving the camera.js
 * examples/camera/world sprite.js
 * examples/collision/bounding box.js
 * examples/collision/group vs group.js
 * examples/collision/larger bounding box.js
 * examples/collision/offset bounding box.js
 * examples/collision/sprite tiles.js
 * examples/collision/sprite vs group.js
 * examples/collision/sprite vs sprite custom.js
 * examples/collision/sprite vs sprite.js
 * examples/collision/transform.js
 * examples/collision/vertical collision.js
 * examples/display/fullscreen.js
 * examples/display/graphics.js
 * examples/display/render crisp.js
 * examples/games/breakout.js
 * examples/games/invaders.js
 * examples/games/starstruck.js
 * examples/games/tanks.js
 * examples/geometry/circle.js
 * examples/geometry/line.js
 * examples/geometry/playing with points.js
 * examples/geometry/rectangle.js
 * examples/geometry/rotate point.js
 * examples/groups/add a sprite to group.js
 * examples/groups/bring a child to top.js
 * examples/groups/bring a group to top.js
 * examples/groups/call all.js
 * examples/groups/create group.js
 * examples/groups/create sprite in a group.js
 * examples/groups/display order.js
 * examples/groups/for each.js
 * examples/groups/get first.js
 * examples/groups/group as layer.js
 * examples/groups/group transform - rotate.js
 * examples/groups/group transform - tween.js
 * examples/groups/group transform.js
 * examples/groups/recyling.js
 * examples/groups/remove.js
 * examples/groups/replace.js
 * examples/groups/set All.js
 * examples/groups/sub groups - group length.js
 * examples/groups/swap children in a group.js
 * examples/input/cursor key movement.js
 * examples/input/drag several sprites.js
 * examples/input/drag.js
 * examples/input/drop limitation.js
 * examples/input/follow mouse.js
 * examples/input/game scale.js
 * examples/input/key.js
 * examples/input/keyboard hotkeys.js
 * examples/input/keyboard justpressed.js
 * examples/input/keyboard.js
 * examples/input/motion lock - horizontal.js
 * examples/input/motion lock - vertical.js
 * examples/input/multi touch.js
 * examples/input/override default controls.js
 * examples/input/pixel perfect click detection.js
 * examples/input/pixelpick - scrolling effect.js
 * examples/input/pixelpick - spritesheet.js
 * examples/input/snap on drag.js
 * examples/loader/pick images from cache.js
 * examples/misc/net.js
 * examples/misc/random generators.js
 * examples/misc/repeatable random numbers.js
 * examples/particles/click burst.js
 * examples/particles/collision.js
 * examples/particles/diamond burst.js
 * examples/particles/no rotation.js
 * examples/particles/random sprite.js
 * examples/particles/when particles collide.js
 * examples/particles/zero gravity.js
 * examples/physics/accelerate to pointer.js
 * examples/physics/angle between.js
 * examples/physics/angle to pointer.js
 * examples/physics/angular acceleration.js
 * examples/physics/angular velocity.js
 * examples/physics/mass velocity test.js
 * examples/physics/move towards object.js
 * examples/physics/multi angle to pointer.js
 * examples/physics/quadtree - collision infos.js
 * examples/physics/quadtree - ids.js
 * examples/physics/shoot the pointer.js
 * examples/physics/sprite bounds.js
 * examples/sprites/add a sprite.js
 * examples/sprites/add several sprites.js
 * examples/sprites/collide world bounds.js
 * examples/sprites/destroy.js
 * examples/sprites/dynamic crop.js
 * examples/sprites/extending sprite demo 1.js
 * examples/sprites/extending sprite demo 2.js
 * examples/sprites/horizontal crop.js
 * examples/sprites/move a sprite.js
 * examples/sprites/out of bounds.js
 * examples/sprites/scale a sprite.js
 * examples/sprites/shared sprite textures.js
 * examples/sprites/sprite rotation.js
 * examples/sprites/spritesheet.js
 * examples/sprites/vertical crop.js
 * examples/text/bitmap fonts.js
 * examples/text/hello arial.js
 * examples/text/kern of duty.js
 * examples/text/remove text.js
 * examples/text/text stroke.js
 * examples/tile sprites/animated tiling sprite.js
 * examples/tile sprites/tiling sprite.js
 * examples/tilemaps/fill tiles.js
 * examples/tilemaps/mapcollide.js
 * examples/tilemaps/mario.js
 * examples/tilemaps/mariotogether.js
 * examples/tilemaps/paint tiles.js
 * examples/tilemaps/randomise tiles.js
 * examples/tilemaps/replace tiles.js
 * examples/tilemaps/sci fly.js
 * examples/tilemaps/supermario.js
 * examples/tilemaps/supermario2.js
 * examples/tilemaps/swap tiles.js
 * examples/tilemaps/wip1.js
 * examples/tilemaps/wip2.js
 * examples/tilemaps/wip3.js
 * examples/tilemaps/wip4.js
 * examples/tweens/bounce.js
 * examples/tweens/bubbles.js
 * examples/tweens/chained tweens.js
 * examples/tweens/combined tweens.js
 * examples/tweens/easing spritesheets.js
 * examples/tweens/easing.js
 * examples/tweens/fading in a sprite.js
 * examples/tweens/pause tween.js
 * examples/tweens/tween several properties.js
 * examples/world/fixed to camera.js
 * examples/world/move around world.js

Extracted 21 categories:
 * animation
 * audio
 * basics
 * buttons
 * camera
 * collision
 * display
 * games
 * geometry
 * groups
 * input
 * loader
 * misc
 * particles
 * physics
 * sprites
 * text
 * tile sprites
 * tilemaps
 * tweens
 * world

Writing examples/_site/examples.json...OK

Done, without errors.
```