WIP: Allow auto creating new terms or selecting existing ones

* Fix taxonomy term integration
* Integrate with select2 on the Angular

Needs some more cleanup, but already working!
![angularjs_form___site-install](https://cloud.githubusercontent.com/assets/125707/3669991/e55c19f6-123d-11e4-9a25-005dd0b5c8b0.jpg)