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
Annotations
ANnotations