Updates .gitignore to exclude .pyo files.
Adds duration inspection for contentload.
Imports additional metadata from files.
Annotates related_content on imported data.
Adds related content to content templates.
Refactors 'learn' routing to route by channels.
Merge branch 'develop' into content_import_additions
First pass at channel based routing.
Auto redirects to current channel.
Fixes url dependent browser test to update with channel namespace.
Merge branch 'develop' into content_import_additions

Conflicts:
	kalite/distributed/static/js/distributed/topics/views.js
Updates all topic navigation to work through URL modification.
Makes navigation check currently rendered topic tree levels, only creating new views for topic nodes that are not already displayed.
Makes remove_topic_views failsafe.
Merge pull request #2518 from rtibbles/content_import_additions

Content import additions
Merge branch 'develop' of github.com:learningequality/ka-lite into nav-polish