WIP - Studio: Group Access Level UI

UX support for statically standing up and styling new UI within containers/components to support group access levels.

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**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

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**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)
@cahrens, happy to scope this down a bit, but how does ``.has-group-visibility-set`` sound? I'd like to keep it a bit more generic group focused knowing that we'll ideally be adding in other types of groups to the modal that relates to this down the road (i.e. Content Experiment Groups),

Make sense and seem cool to you?