Fix CSS "content" rules for buttons (add space)
Simplify a translation
Add some translations for future use
Add a CSS rule for presentational styling
Work on use of constants for attribute lists
Change index pages into table form
Fix and shorten a translation
On login, redirect to org/participants
Replace 'participants_to_approve' page

Remove 'participants_to_approve' organizers page, add a page for participants with talk proposals instead.
Remove participants_with_talk_proposals tab

Remove participants_with_talk_proposals utility tab (because now there is a separate page for this).