Upgrade angular to 1.2.0 and Grails to 2.3.1

Hi,

I have forked and upgraded the plugin. If you think, this is useful upgrade, please accept the pull request.

Issue #9 . I removed angular-autobind from the code and documentation.
Issue #8. Unclear usage. I updated the "Usage" docs. Hopefully, it becomes clearer.
Issue #7. Missing angular-resource. Angular resources and other angular files are included.
Issue #6. Resource plugin updated to 1.2.1