Add osx build version

For build this version on OSX, i use : 

- gcc 4.7.2 (custom build on osx)
- XUL.framework (http://ftp.mozilla.org/pub/mozilla.org/xulrunner/releases/18.0.1/runtimes/)
- xulrunner_sdk x86_64 (http://ftp.mozilla.org/pub/mozilla.org/xulrunner/releases/18.0.1/sdk/)