WIP on votes
Rename Suggestion#vote_for(user) → vote_by(user)
New vote types
New votes are now considered the same as a "pass" vote
Voting works now

Needs more UI love, though.
Super important: play with the "Delete suggestion" button's style
Ignore non-persisted votes when checking if a suggestion can be deleted
Voting form on one line and with submit on change
"Delete suggestion" button UI improvements

- Move it next to the suggestion itself
- Don't display it as a red DANGER button unless when in a :hover state
Ajaxify voting