lib/snoo/subreddits.rb
def ban_user container, user, subreddit
      friend_wrapper container: container, name: user, r: subreddit, type: "banned"
    end
def ban_user container, user, subreddit
      friend_wrapper container: container, name: user, r: subreddit, type: "banned"
    end
Ban a user from a subreddit

 @param (see #add_moderator)
 @return (see #clear_sessions)