add support for multiple states.

* modify tests to fit the multistate case.
* regenerate dist/

The used classList API only allows `add()` being called with a single
class. Therefore if your data-bespoke-state attribute contains multiple
classes, it throws an exception.

When might this happen? For example when you are having transitions
isolated into own classes, so we can swap them between slides.
Merge pull request #2 from originell/multistate-final

Add support for multiple states.