feat(typeahead): Adds extra 'traversal' behaviors.

[kdschaffe]

Traversal Extras

• Changes input text to 'traversed' item while arrowing through results.
• Restores originally typed text when traversing out of results, and back to the input.
• Allows arrowing to loop in both directions.
• Prevents select event while traversing (need to click or hit enter)
• Escape clears suggested results and restores originally typed value.

TODO

This code has been tested in a production environment for many months now but may not be ready to be merged here. Since the state of the project is in limbo I wanted wait to see if it's worth the time do complete what's left. Here's a quick list.

• Add one or more directive attributes to turn extras on/off
• Solve for conflicts with focusFirst behavior (as is, typeahead-focus-first="false" is needed)
• Fix / Update failed tests
• Create related tests

Maintainers feel free to chime in and let me know if you'd want this merged or if anyone thinks its worth the time.