Raise Registry AMI events on registration failures

This patch makes it so that all registration attempts that fail that
also permanently modify the registration state will raise an appropriate
AMI event.

Note that this patch was forward ported to trunk and the Stasis Core
message bus by mjordan.

(closes issue ASTERISK-21368)
Reported by: Dmitriy Serov
patches:
  chan_sip.c.diff uploaded by Demon (license 6479)



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@395907 65c4cc65-6c06-0410-ace0-fbb531ad65f3