FreeSWITCH

Merge pull request #1718 in FS/freeswitch from ~INFOMIND/freeswitch:bugfix/FS-11826-mod_conference-channel-variables_join to master

* commit 'b7bce76da5b496400bbd9cce1f53b0be5b4b0ae1':
  FS-11826 [mod_conference] conference_member.c: channel variables (conference_join_) Fixes variables being seen as empty and proper range on conference_join_energy_level