Add CEL extra field to cel_pgsql.

(closes issue #18462)
Reported by: joscas
Patches:
      bug_18462.diff uploaded by snuffy (license 35)
      cel_pgsql.conf.sample.issue18462.patch uploaded by joscas (license 1180)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@317482 65c4cc65-6c06-0410-ace0-fbb531ad65f3