Add manager events for RTCP statistics.

Also adds a new "reporting" permission for manager, since it can be incredibly spammy.
  This permission was discussed on the -dev mailing list some months back.

Issue 8613, patch by johann8384, with some minor changes by me.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@70961 65c4cc65-6c06-0410-ace0-fbb531ad65f3