Handle errors in setting resource files.

Closes #378.
For future, we should probably replace Option[JsValue] with Either or
Try in order to propagate better error information back to the
controllers.
Cleanup the Related Docs template.
Hide "Add Content" button if user lacks permission.

Closes #309
Shift config errors in templates to the client.

Closes #302
Make links in text annotations open in new tabs.

Closes #277
Fix spacebar play/pause function.
Shift language select button for definitions.

Temporary fix for #377
Remove content from course page functionality added.

Also fixed the BOOM! it broke issue when you submit the addMyContent
modal without selecting anything.
Update UI for visibility/shareability
Also consolidate handling of vis/share changes into the normal settings update methods on the server. Still need to rework the actual underlying storage.
Track multiple save locations.

Addresses #300
Basic data access to enable setting save location.
Allow tracking multiple save locations.

Closes #300
Allows user to delete copies of same content in Course