1st attempt to support i18n in dates and times

All right, folks, here is my first attempt to integrate some support for localized dates, times, date intervals and things like "just now", "1mo", etc.

It seems to me that the support in Sugar JS is very cool and extensible, so I replaced humane.js with Sugar's integrated Date class. I added extra support for "just now", because this is not implemented in Sugar.

CZ locale in not present in Sugar, so I wrote it myself, and their system is great, because they allow you to supply custom language inflection and all this stuff.

As always, changes & fixes are more than welcome. Please review and let me know if this approach is acceptable.