Add mobile-friendly versions

Summary:
Unfortunately this wallpaper is very landscape-centric in design,
so it is not very mobile-friendly. This patch is an attempt at a
crop that will at least produce a better result than the automatic
crop.

Reviewers: VDG, bshah

Reviewed By: bshah

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D29727