fixed officer page spacing, clear:left to clear:both
Sidebar no longer pushes down officer photos
"ajaxified" signups#mark for /events/:event_id

Note:
Any authenticated user can mark other users as attended.
Added css cursor:pointer for all .button_to links
added signups#edit and signups#update actions and routes
Note: Users cannot currently destroy signups. This may be an important
statistic to see the ratio of actual attendance to signups.
replaced slider images with 2012 images
revised permissions to allow normal users to view events page
solved merge conflict for officer page styling