Add the 'E' option to exit ChanSpy, once the single channel it spied upon hangs up.

In addition, there's a bit of cleanup to the arguments and documentation, in which
I discovered that the last feature added to this application duplicated an option
(oops!) and changed that option so that it now works.
(closes issue #14909)
 Reported by: junky
 Patches: 
       __20090901-spy_hangup_trunk.diff uploaded by lmadsen (license 10)
 Tested by: amilcar, junky, flujan, lmadsen


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@219105 65c4cc65-6c06-0410-ace0-fbb531ad65f3