D13034: Add mechanism to notify other clients of config changes over DBus

[David Edmundson]

davidedmundson added dependencies: D13033: Expose getter method for 
KConfig::addConfigSources, D13032: Fix cleanup of kconfigtest kdeglobals.

REPOSITORY
  R237 KConfig

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D13034

To: davidedmundson, broulik
Cc: broulik, zzag, kde-frameworks-devel, michaelh, ngraham, bruns