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)
If this message might be used for other types of groups too, then perhaps generically refer to "groups" rather than "content groups"? I'm not sure enough of the context. Also need to change "access" to "visible".
Perhaps: "The selected group no longer exists. Choose another group or make the component visible to All Students and Staff" (make sure case for **All Students and Staff** matches option text).