WIP - Studio: Group Access Level UI

UX support for statically standing up and styling new UI within containers/components to support group access levels.

- - -

**Background**
* JIRA Story/Spec - https://openedx.atlassian.net/browse/TNL-652
* UI Design - http://invis.io/K21UDOV7H
* Sandbox Unit Page Example - http://studio.talbs.m.sandbox.edx.org/container/i4x://edX/DemoX/vertical/vertical_0270f6de40fc

- - -

**Screenshot - Combined Modal UI**
![screenshot-localhost 8001 2014-12-09 19-23-58](https://cloud.githubusercontent.com/assets/163763/5368828/19dafe78-7fd9-11e4-970a-38dfc73a4bfc.png)

**Screenshot - Container/Unit View Tweaks**
![screenshot-localhost 8001 2014-12-09 19-24-36](https://cloud.githubusercontent.com/assets/163763/5368831/1f777e1a-7fd9-11e4-9a01-2fee6a92a9e4.png)
@talbs Since "visibility" is pretty overloaded (current "visibility" states are related to publish state, locking, etc.), can we make it explicitly about content groups? Perhaps "has-content-group-visibility-set"?