Fix keyboard interface for typeahead control

The keyboard part of the interface was actually working perfectly; what
was wrong was the UI elements that displayed the highlight. First, the
active class needed to have a background highlight color, and second,
the directive needed to stop clobbering the "items" list passed to it by
the calling code. Finally, the calling code needed to pass the list of
items (which would be set by the search function) rather than an individual
item: e.g., "users" instead of "user".