Add option 'randomperiodicannounce' to queues.conf. Setting this will

allow the list of periodic announcments specified to be played in a random
order instead of being played sequentially.

(closes issue #6681)
Reported by: alt_phil
Tested by: putnopvut



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@109621 65c4cc65-6c06-0410-ace0-fbb531ad65f3