Create the 'About content' widget

There should be an aboutcontent widget that has 2 different tabs. The first tab is the Details tab and shows the metadata of the content (title, description, url, created by). When a description is not available, it should not be shown. The second tab is the Shared with tab and shows the list of members of the content.
Contrary to the designs, this will need to be moved back to the left to roughly achieve the following result:

![screen shot 2014-07-10 at 17 39 18](https://cloud.githubusercontent.com/assets/109850/3541889/d20d0244-0850-11e4-8414-02d7a046274a.png)