Fixes for Audio Support Detection, Texture Support in Particle System and Performance improvements

This pull requests contains the following additions / fixes:

- Added support for detecting audio support for mp4 and m4a (`CocosDenshion/SimpleAudioEngine.js`)
- Added support for using PNG data from .plist files in the ParticleSystem (`cocos2d/particle_nodes/CCParticleSystem.js` and `cocos2d/particle_nodes/CCParticleSystemQuad.js`)
- Fix for incorrect values being returned by `cc.getHTMLElementPosition` (`cocos2d/touch_dispatcher/CCTouchDispatcher.js`)
- Fix for missing caching in `cc.generateTextureCacheForColor` (`cocos2d/sprite_nodes/CCSprite.js`). Before the fix numerous blending operations splitted the image channels on every frame. The fix results in huge performance improvements across the board, and especially in IE 9 and 10