Remove pointless IE event compatibility stuff.
Remove JQuery. Final elimination of Mustache.

Page layout is now ready to be ractivized or integrated into the Ayamel
Player.

Having started looking into the annotation system, it appears that Josh
at some point completely replaced the original TIARA text annotation
system with a less efficient from-scratch system. Need to do some
further investigation to see how the data model may have been changed.
This is going to complicate the creation of the Text Viewer.
Fix add-content-to-course dialog.