[notready] List user's sources

Still needs a lot of work, but the basics are in place:
![list-sources](https://cloud.githubusercontent.com/assets/108094/2746127/e19d8590-c740-11e3-8517-a2fe720f0807.gif)

Todo:

- [ ] Error handling
- [ ] Empty state
- [ ] Style adjustments
- [ ] Code review from someone who actually knows javascript