adds nested comments
adds form to create top level comments
finishes replying to comments
creates basic portal/logged_in headers
updates basic index view
adds prev/next buttons
creates UserVote model and sets up associations
finishes upvote/downvote actions in photos controller
finishes favorite/unfavorite buttons
removes favorite column from photo and creates favorite model
fixes favorite/unfavorite button
creates my images/my favorites views
updates browse buttons to disappear if there is no next/prev
minor css updates