added SharpZlib code in iOS & Android projects and updated the namespace...

added SharpZlib code in iOS & Android projects and updated the namespace to Cocos2D.Compression.ICSharpCode.SharpZipLib (only for iOS & Android)

=> this follows the same approach as zlib.dll (code has also been integrated, removing the need to use an extra dependancy)
=> other platforms need to do the same
=> XBOX uses a special build, so the code must reflect that