Add support for Moment.js 2.0

No feature added, just fixes for Moment.js 2.0 (and missing commas detected by newest CoffeeScript).

Remarks:
- moment.js and moment.min.js are duplicated between directories bin/ and lib/
- 3 tests are dependent on the current year and passing from 2012 -> 2013 broke them
- I didn't commit the generated files (twix.js, twix.min.js and twix.spec.js) in order to not pollute this pull request

Thanks for this wonderful little library!