Attempt to simplify talk voting pages

Attempt to simplify talk voting pages

This merges a couple of changes:

1. Each individual vote is cast by selection in dropdown and is
   immediately ajax-posted to the backend, so there is no huge save
   button for everything that risks overwriting other fields. Changing
   the vote will automatically update the average value based on the
   changes (and other changes made by others).
2. No dedicated text-edit box for own comments. Instead, own comments
   are listed alongside other comments, and there is an edit button that
   brings up a popup and lets the comment be edited.
3. No popup windows for talk descriptions. Instead, accordions are used,
   so clicking the title will expand the description in-line. This also
   makes it a lot easier to handle things like copy/paste from the
   descriptions.