app_confbridge: Fix ref leak in CLI "confbridge kick" command.

Fixed ref leak in the CLI "confbridge kick" command when the channel to be
kicked was not in the conference.
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Merged revisions 413451 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 413452 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@413453 65c4cc65-6c06-0410-ace0-fbb531ad65f3