Content display fixes

Fixes #2600, resolves #2607, and closes #2608.

Summary of changes:
* Adds border styles to sidebar-tab and sidebar.
* Fixes sidebar-tab positioning.
* Uses content-wrapper template in video-wrapper view to give consistent metadata display across content types.
* Sorts topic tree nodes alphanumerically during content load channel import.

@jamalex You made these issues, care to take a look?