More presenter notes cleanups

Add a section tag around the presenter notes div. It's not clear
why, but this seems necessary to have the notes actually appear
in the presenter console view.

Hide the redundant "Note" title on the presenter note view.

Change-Id: I111c7cbfd4e404f7ff97341123585c2dfc893cd6
Merge pull request #34 from dhellmann/fix-presenter-note-in-console

More presenter notes cleanups