FreeSWITCH-FS-6836

Merge pull request #338 in FS/freeswitch from ~DRAGOS_OANCEA/freeswitch-dragos:opus-ptime-60ms-support to master

* commit '76bdd2b0d57e63a0d59bf78088af25ec733b7426':
  FS-7809: mod_opus: added 60 ms ptime for Opus at 8 khz  ( opus@8000h@60i )