D23196: have the app icon as fallback icon in Snore

[Piyush Aggarwal]

brute4s99 added a reviewer: broulik.

REPOSITORY
  R289 KNotifications

REVISION DETAIL
  https://phabricator.kde.org/D23196

To: brute4s99, #frameworks, broulik
Cc: broulik, kde-frameworks-devel, LeGast00n, michaelh, ngraham, bruns