Broccolification

Eventually the Ruby/Rake dependency will be removed and we will have JavaScript only stuff: Grunt.js for uploading assets to S3 and Broccoli for fast (re)building of this lib.

**TODO**
- [ ] add Grunt.js (JSHint, tests, S3 upload)
- [ ] remove Ruby related stuff
- [ ] verify new builds
- [ ] profit

This will hopefully close #8.