Bower / Wiredep SCSS automatic import

[Wiredep](https://github.com/taptapship/wiredep) / [Grunt-Wiredep](https://github.com/stephenplusplus/grunt-wiredep) uses the [main attribute in bower.json](http://bower.io/docs/creating-packages/) to determine what assets to reference in its injected blocks. As the font-awesome.scss file is not defined, it is not discovered and subsequently is not injected into wiredep sections.

The fix is simply to add the reference to the main font-awesome.scss file to the main attribute value array, implemented in this pull request.