Improve main

Most of the work for voting on posts is done here. However, it is not functional currently since we need to modify the vote_up method in the posts_controller on server-side to NOT depend on current_user. 

This change will actually require changes in a few places (in particular, at least for the publish button), but we need some persistent way to communicate the logged in user on Android to the server. 

Pushing this now since the voting button shouldn't affect anything else, and there are some other improvements here (fixing popular ads).