likes are nested resources (only create&destroy) for posts&comments.
added authoring for topics&posts&comments.
likable objects can be liked only once by each user.
renamed likes to opinions. they can have negative/positive value (likes/dislikes).
opinions change is now broadcast, with different behaviour for issuing client (she refreshes the whole post/comment entry, while the others just refresh the counters).
users can only modify/delete their own topics/posts/comments. added seeds with seedbank gem.
Merge pull request #3 from gatperdut/add_likes_to_posts_and_comments

Add likes to posts and comments