FreeSWITCH

Merge pull request #1088 in FS/freeswitch from ~ROMANAT/freeswitch:feature/FS-9734-add-channel-vars-att_xfer to master

* commit 'c20fa5e8f7cef34086c26ef6e0bbd81b2be7df4b':
  FS-9734: updated keys to be set in memory on att_xfer execution