Move to standard D-Bus integration for windows-service

[ederag]

hamster.desktop (and stuff currently handled by hamster-windows-service)
should be improved to comply with
https://wiki.gnome.org/HowDoI/DBusApplicationLaunching

Only the database server part (hamster-service) should stay separated.

The current hamster-windows-service (org.gnome.Hamster.WindowServer) is legacy,
the main app (hamster-cli.py, installed as hamster), should replace it,
since it holds a gtk.Application with the same id (org.gnome.Hamster.WindowServer):

hamster/src/hamster-cli.py

Lines 92 to 97 in 4417b73

	class Hamster(gtk.Application):
	def __init__(self):
	# inactivity_timeout: How long (ms) the service should stay alive
	# after all windows have been closed.
	gtk.Application.__init__(self,
	application_id="org.gnome.Hamster.WindowServer",

wip: #536

[ederag]

#536 seems to comply with recommendations,
but was based on the assumption that the new style dbus interface (--gapplication-service)
was a drop-in replacement for the old separate org.gnome.Hamster.WindowServer
(hamster-windows-service). It's not.
The service is started, but there are no methods corresponding to the actions.
The actions have to be activated in a completely different way.
So this is not backward compatible. The gnome-shell-extension cannot work with it.
We'll need three dbus ids:

1. database server (org.gnome.Hamster). Can't change the name, it's used by the extension.
2. new one for the Gtk.Application: org.gnome.Hamster.GtkApplication ?
3. deprecated legacy org.gnome.Hamster.WindowServer that will redirect to the new one.

Or find a way to add the methods to the app connection ?

It would be great if anyone could help, please say so.
Card moved to "todo" because I need to focus on my main job again.

[ederag]

#538 seems to be better.