Cleanup Spec format, and add failing test for #307
moved the anchorPoint test into a dedicated test unit

I will add there the test on the visible flag
fixed computed value of `me.device.isMobile` when running in a desktop browser (was `null` instead of `false`)
[#317] avoid overwriting the entity visible flag with the group one
[#316] Convert key bindings from Boolean to a reference counter
[#316] Update CHANGELOG
[#316] Replace `delete` with assign to `undefined`.
updated the `grunt-contrib-uglify` plugin to last 0.2.7 version
[#307] if defined, call the object `onResetEvent` callback when being re-instantiated through the entity pool
Fix some jshist errors.
[#316] Prevent keyStatus from becoming negative.

- Fixes a false-positive keypress when releasing a key after it has been rebinded.
added the debug panel to the whack-a-mole example
enabled the use of me.Tween objects with the Object Pooling feature

`EntityPool` probably need some renaming :)
reused me.Tween object when possible for the fadeIn/fadeOut effect
reused me.Tween object in the whack'a'mole example
Sync'ed with master