#765 MIME type handler for .sh3d files not installed or working in Kubuntu 17.04

[Nathaniel Graham]

Steps to reproduce:

1. Install SweetHome3D on Kubuntu 17.04, running KDE Plasma 5.9.4
2. Create a new document
3. Save it in the default file format as <something>.sh3d</something>
4. Navigate to the file in Dolphin
5. Open the file

Expected results:
Dolphin opens the file with SweetHome3D

Actual results:
Dolphin (correctly) identifies the file as a zip archive based on its MIME type, but then opens it with Ark--the archive manager--instead of SweetHome3D. It seems that SweetHome3D does not install a MIME type handler for its .sh3d file type:

grep -ri sh3d /usr/share/mime/application/ | wc -l
0