FreeSWITCH-FS-8767

Merge pull request #669 in FS/freeswitch from ~ICEHESS/freeswitch:feature/FS-8737-add-bill_msec-variable-to-default to master

* commit 'dee37afbb34990dea5d77e038cd5f55212893b97':
  FS-8737: [mod_kazoo] Add require vars to default filter