Cleanup config cache on exit.

(issue ASTERISK-20649)
Reported by: Corey Farrell
Patches:
      config-cleanup-all.patch (license #5909) patch uploaded by Corey Farrell
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Merged revisions 377104 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 377105 from http://svn.asterisk.org/svn/asterisk/branches/10
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Merged revisions 377106 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@377107 65c4cc65-6c06-0410-ace0-fbb531ad65f3