Angular-UI autocomplete wrapper

Hello,

I've created a wrapper for the jQueryUI autocomplete widget (based on Angular-UI's date directive). This does have a known bug where selecting a suggestion via mouseclick does not cause the model to update (but using arrow keys + return does update the model). jQueryUI's autocomplete doesn't have an equivalent `.getDate()` method to get the selected item, so I used `element.val()`, which does not seem to update when the select event is fired from mouseclick.

This directive supports uiConfig and extends the defaults with a scope object passed from uiAutocomplete.

I saw #414, but the code didn't feel like it came from the AngularUI, and the way it required functions in the controller did not seem to be the "Angular Way" of doing things.

P.S. Sorry if I've done this pull request incorrectly—I'm new to Github and this is my first PR.