[Example] Automatically select if only one element

[dsnoeck]

Bug description:

Example of a custom directive which automatically select the only entry if the ui-select has only one element.

Link to minimally-working plunker that reproduces the issue:

http://plnkr.co/edit/2JUXBErSJYDJBKhv3XuC?p=preview

Version of Angular, UI-Select, and Bootstrap/Select2/Selectize CSS

Angular: 1.7.2 UI-Select: 0.19.7