Support Mac OSX 10.10

1. Replaced JSONKit with native Cocoa JSON API. Maybe performance will be worse then JSONKit.
2. Replaced JSCocoa with JavaScriptCore APIs. JSCocoa need newer version SDK, so I had replaced Xcode project file `MACOSX_DEPLOYMENT_TARGET` value from 10.7 to 10.10 which may introduce compatibility issues.


*TODO:* Only tested text mate plugin on OS X 10.10, many other tests
should be done.