Activity items identity themselves as `Image`

![screen shot 2014-08-19 at 16 48 09](https://cloud.githubusercontent.com/assets/109850/3968586/4c4af5ee-27b8-11e4-9fe4-4b8a5fcdf06b.png)

Actually, because search API output is different than library API output, it probably makes sense to set up the following

1. Create two users, 4 content items, a group and a discussion
2. Check that the content items show as expected in the library
3. Check that the discussion shows as expected in the library
4. Check that the group shows as expected in the library
5. Follow a user
6. Check that the user shows as expected in the network
7. Do a search for everything and make sure all items show as expected