Update obfuscate.xml

there is no file obfuscate_exclude_cocos2d in v2.x .

in 2.2.3 obfuscate_exclude_cocos2d.js ,should add 
CSSProperties.prototype.getTargetPlatform; 
CSSProperties.prototype.setKeypadEnabled; 
CSSProperties.prototype.ccs; 
CSSProperties.prototype.UILayer;   (ccs.UILayer.create())
......

so many  works   like  a.b.c()   ,it would be obfuscated!!