Python gdbus example server

[Tony Asleson <tasleson redhat com>]

In an effort to learn & understand writing a dbus service with python
via PyGI, I attempted to convert the C example:

https://git.gnome.org/browse/glib/tree/gio/tests/gdbus-example-server.c

to python:

https://github.com/tasleson/py-gdbus-example-server/blob/master/py-gdbus-example-server.py

I had to patch glib to include:
https://bug656325.bugzilla-attachments.gnome.org/attachment.cgi?id=288258

to make this work as far as it does.

I would really appreciate those that understand the library better to
take a peek and offer suggestions for those parts which I couldn't find
/ figure out.  They are littered around the code in TODO comments.

Most notable:
- How do I find the corresponding constants for things like:
  G_IO_ERROR, G_IO_ERROR_FAILED, G_DBUS_ERROR_MATCH_RULE_NOT_FOUND and
  others?
- How does one call GLib.set_error_literal correctly?
- Is there a better way to create variant type instead of doing
  something like this:

   p1 = GLib.Variant('s', str(interface_name))
   p2 = GLib.Variant('a{sv}',
                     {'Title': GLib.Variant('s', title)})
   p3 = GLib.Variant('as', ())
   values = GLib.Variant.new_tuple(p1, p2, p3)

Getting this example working this far wasn't very straight forward.
There is a dearth of documentation and examples on this subject, thus
the reason I posted the code.

Thanks!

Regards,
Tony