Add round robin to chan_zap with use of Zap/r<number>/<exten> (ascending) or...

Add round robin to chan_zap with use of Zap/r<number>/<exten> (ascending) or Zap/R<number>/<exten> (descending).


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@1707 65c4cc65-6c06-0410-ace0-fbb531ad65f3