Creative Commons Licensing for edX

This PR adds Creative Commons Licensing to the Open edX Platform.

Review tickets
T&L https://openedx.atlassian.net/browse/TNL-195
UX https://openedx.atlassian.net/browse/UX-948
All of this logic to set and remove classes should be handled in the `render()` function. Once you have a model to back this view, you want to set your license property on the model, which will trigger a `change` event, which your view can hook into to re-render itself. Then, the view can apply whatever classes are necessary based on the attributes of the model.