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.
Hrm - would be an argument that does nothing, though - as the channel routing is done client side. I guess we need to have a general framework for how to run tests on URLs that are generated and navigated solely on the client.