FreeSWITCH-FS-6836

Merge pull request #887 in FS/freeswitch from ~MZAKA/freeswitch:feature/FS-9276-proxy-notify-info to master

* commit '589a0e682e67054bd1b2f351629b0af0e5ec3035':
  FS-9276 new feature proxy in-dialog calls sip notify and info similar to proxy hold