Content import additions

Summary of changes:
* Inspects media files for metadata during content import
* Inspects json metadata for related content files
* Adds starting template for related content
* Updates 'learn' router scheme to be namespaced by channel

@jamalex @aronasorman please review.
Tada!
![image](https://cloud.githubusercontent.com/assets/1680573/4744038/dc70f910-5a2c-11e4-899e-c309c2aa056b.png)