angular-ui/ui-select — pull request #49 by just-boris (2014-04-08 13:41:01+00:00)
Title: Add choices grouping using 'group by' expression

As described in #48, I've done options grouping.
Here is [plunker](http://plnkr.co/edit/qvVKhG?p=preview) where you can see this changes in action.