- allow configuring lock settings from config.xml
 - fix https://code.google.com/p/bigbluebutton/issues/detail?id=1773
Merge branch 'merge-polling-with-master' into allow-meeting-to-be-extended

Conflicts:
	bigbluebutton-apps/src/main/scala/org/bigbluebutton/core/MeetingActor.scala
	bigbluebutton-apps/src/main/scala/org/bigbluebutton/core/apps/users/UsersApp.scala