title: add new item to typeahead if it's not on the list
body: <p>I'm using angular bootstrap typeahead.  I would like to make an enhancement where if the item is not in the list, the user has the ability to add a new item (maybe the item being typed shows up at the bottom of the list with a plus button, or something similar).</p>
  
  <p>Is there an easy way to make this enhancement?  If not, is there something else that can do this?</p>