Angular-UI autocomplete wrapper

Hello,

I've created a wrapper for the jQueryUI autocomplete widget (based on uiDate). ~~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.~~ (fixed in 92778051028800958587282b4671982e5b0ac6bd)

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. Also, I couldn't get it to work.

P.S. Sorry if I've done this pull request incorrectly—I'm new to Github and this is my first PR.