cel: Make sure channels in extra fields include their unique IDs as well

CEL typically tracks a lot of information using the unique ID of the channel.
This is typically needed due to tying events together using the linked ID of
the various channels involved in a "call", which is derived from the channel ID
of the oldest channel involved in a bridge (or in the case of a Dial, the
parent channel).

Previously, we had updated the extra fields to include the involved channel
names, but forgot to put in the unique ID. This patch corrects that error.
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Merged revisions 421037 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 421042 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@421043 f38db490-d61c-443f-a65b-d21fe96a405b