Added a message for when a default presentation pod is created

...e/apps/presentationpod/CreateDefaultPresentationPod.scala

.../presentationpod/CreateNewPresentationPodPubMsgHdlr.scala

...tton/core/apps/presentationpod/PresentationPodHdlrs.scala

...utton/core/apps/presentationpod/PresentationPodsApp.scala

...n/scala/org/bigbluebutton/core/running/MeetingActor.scala

.../org/bigbluebutton/core2/message/senders/MsgBuilder.scala