Improve COllision docs

Adds practical examples to the collision features introduced in #699 .
Merge pull request #774 from FallSe7en/develop

Fix for propogating 90deg rotations to child entities
Merge pull request #768 from mucaho/collision_docs

Improve Collision docs
Add additional game loop events

Fixes #478 .
Add audio_isPlaying.
Refactor "Delay" to use dt from frameData

Rather than explicitly requesting the current time, the "Delay" component should just accumulate the time passed in by the "EnterFrame" event.  This way it doesn't need to worry about tracking the pause state of the game; that's all handled by the main game loop.

This meant drastically simplifying the tests -- they no longer need to overwrite the Date object or anything like that.
Merge pull request #775 from starwed/simpler-delay

Refactor "Delay" to use dt from frameData
Refactored loader; created function 'removeAssets'; fixed bug in Crafty.audio.remove
Merge pull request #778 from mucaho/audio_isPlaying

Add audio_isPlaying.
Merge pull request #769 from mucaho/more_events

Add additional game loop events
Merge pull request #777 from heniotierra/loader_refactored

Refactored loader, and created new function 'removeAssets'
Update DOM.js
Merge pull request #779 from truman/develop

Update DOM.js documentation typo
Update viewport.js
Merge pull request #784 from im007boy/patch-1

Update viewport.js
Add cancelAnimationFrame as it is the primary way to cancel Fixed #796

cancelAnimationFrame was missing and it causes an error in Chrome.
Cache travis-ci modules
Make a main file that requires all the files

This makes it possible to require crafty without compiling it first.
Also by defining main in package.json require can automatically
pick it up from the root folder if you are using browserify.
Fix error where a string is used instead of a array
Merge pull request #800 from kevinsimper/fixSoundDocError

Fix error where a string is used instead of a array