define chats
Merge remote-tracking branch 'origin/expandable-browse' into define-chats
user can 'like' others once

creates chat with involved users
update seed data for chat testing
fix 'both' preference index conditions
user can update an existing chat by liking someone back
user cannot join a chat twice
Merge pull request #9 from maxkohl88/define-chats

Define chats
Merge remote-tracking branch 'origin/master' into conversation-matches
pushing up this branch for jake to pull down and merge into his branch