transmission-gtk: fix gsettings schemas, closes #2295
spacefm: fix gsettings schemas

Could not test it as the application did not start
for other reasons.
midori: fix gsettings schemas

Could not test it because it does not compile for other reasons.
transmission-remote-gtk: fix gsettings schemas
gnumeric: fix gsettings schemas
pitivi: fix gsettings schemas, depend upon gnome-desktop
Merge pull request #2300 from lethalman/gsettings

Fix gsettings schemas for several gtk3 apps