Persist password (#393)

* never hold the owner of the room on the waiting screen

* persist room passwords so we can always call create meeting, even if it's already running, to avoid any inconsistency or race condition when joining a meeting

* Fixed issues in migration, room attribute updates, random_password and tests

app/controllers/rooms_controller.rb

@@ -90,7 +90,7 @@ class RoomsController < ApplicationController
       end
     end
 
-    if @room.running?
+    if @room.running? || @room.owned_by?(current_user)
       # Determine if the user needs to join as a moderator.
       opts[:user_is_moderator] = @room.owned_by?(current_user)