Let users log out

--verifying that users don't have the same name will be done through coffeescript with pusher
I'm still not sure how to implement this functionality... my instinct is to do something like:

```ruby
class RoomSession
  def initialize
    ...
    @@session_list << self
  end
  def self.allowed_to_access?(room, session)
    @@session_list.find(session).include?(room.id)
  end
end
'''
which seems horrific