D5149: Cache screenshots to avoid downloading them over and over

[Aleix Pol Gonzalez]

apol requested changes to this revision.
This revision now requires changes to proceed.

REPOSITORY
  R134 Discover Software Store

REVISION DETAIL
  https://phabricator.kde.org/D5149

To: jgrulich, apol
Cc: plasma-devel, progwolff, lesliezhai, ali-mohamed, jensreuterberg, abetts, 
sebas, apol