Multiple dataset support & renamed events

This is a pretty major release that involves some breaking changes.

Some events have been renamed (again). Sorry about that, but I just wasn't happy with them.
I believe the new event names make much more sense and are semantically correct.

• tokenfield:preparetoken is now tokenfield:createtoken
• tokenfield:createtoken is now tokenfield:createdtoken

There are 2 new events:

• tokenfield:editedtoken - fires when a token is ready for editing
• tokenfield:removedtoken - fires after a token is removed from DOM

Other changes and improvements in this release:

• Fixed css path in bower.json #100
• Edit mode fixed when only one token present
• Support readonly inputs
• minLength is now tested against label, instead of value
• Always pass full datum object to typeahead events #116
• Multiple datasets for Typeahead are now supported
• Built-in event handlers can now be cancelled on some events by calling event.preventDefault() or doing return false