CallCompletionRequest()/CallCompletionCancel() exit non-zero if fail.

CallCompletionRequest()/CallCompletionCancel() exit non-zero if fail.

The CallCompletionRequest()/CallCompletionCancel() dialplan applications
exit nonzero on normal failure conditions.  The nonzero exit causes the
dialplan to hangup immediately.  The dialplan author has no opportunity to
report success/failure to the user.

* Made always return zero so the dialplan can continue.

* Made set CC_REQUEST_RESULT/CC_REQUEST_REASON and
CC_CANCEL_RESULT/CC_CANCEL_REASON channel variables respectively.  Also
documented the values set.

* Reduced the warning about no core instance in CallCompletionCancel() to
a debug message.  It is a normal event and should not be output at the
WARNING level.

(closes issue #18763)
Reported by: p_lindheimer
Patches:
      ccss.patch uploaded by p lindheimer (license 558) Modified
Tested by: p_lindheimer, rmudgett

JIRA SWP-3042

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@312461 65c4cc65-6c06-0410-ace0-fbb531ad65f3