FreeSWITCH-FS-8767

Merge pull request #445 in FS/freeswitch from bugfix/FS-8066-url-for-avatar-not-being-passed-in to master

* commit '3cedeaa67ebb25b0f7aa620aa530cac68311c0b3':
  FS-8066 Add encoded avatar url to userVariables so that mod_conference can use it when no video, or video mute