Add periodic jitter stats to CLI and manager.

(closes issue #8188)
Reported by: stevedavies
Patches:
      jblogging-trunk.patch uploaded by stevedavies
      jblogging-trunk_wmgrevent.patch uploaded by johann8384
      updated_jbloggin-trunk_mgrevent.patch uploaded by johann8384 (license 190)
      (with additional changes by me)
Tested by: stevedavies, johann8384


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@103677 65c4cc65-6c06-0410-ace0-fbb531ad65f3