cel_manager: Don't crash if configuration file is invalid.

The cel_manager module did not properly handle the case where the
configuration file was invalid. The module will now output a warning
message and disable itself if this occurs.

Reported by: Bryan Walters
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Merged revisions 405581 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 405582 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@405583 f38db490-d61c-443f-a65b-d21fe96a405b
Include CHANGES info for r405553

git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@405585 f38db490-d61c-443f-a65b-d21fe96a405b
Remove subversion conflict tag accidentally left in CHANGES

git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@405587 f38db490-d61c-443f-a65b-d21fe96a405b