Revert "Use NoDisplay=true instead of NotShowIn=GNOME;"

This reverts commit b30fb0e2e6e6ce160288cee4a63d926f20852b43.

Turns out we really want to only hide the settings UI only in desktops
which will run it from their control center, or similar centralized
tool.

Right now, that means GNOME.

But we can't hide from the menus of other desktops like KDE, MATE,
etc... or users will never be able to change their settings.

Also, the problems exposed in the original commit we are now reverting
will disappear once we get through bug #15.
Set the settings window type to dialog

This was advised by mclasen on #gnome-design.

We're not an application, just a settings dialog.

This si part of fixing bug #15
Help intltool find the translatable strings in the setup ui

This is part of fixing bug #1