Allow the AMI Hangup command to accept a Cause header.

(closes issue #14695)
Reported by: mneuhauser
Patches:
      cause-for-hangup-manager-action.patch uploaded by mneuhauser (license 425)



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@185704 65c4cc65-6c06-0410-ace0-fbb531ad65f3