D20047: Add X-GNOME-UsesNotifications as recognized key

[Nathaniel Graham]

ngraham accepted this revision.

REPOSITORY
  R309 KService

REVISION DETAIL
  https://phabricator.kde.org/D20047

To: broulik, #frameworks, apol, ngraham
Cc: kde-frameworks-devel, michaelh, ngraham, bruns