Run with flatpak

[albfan]

branch "flatpak" has a tentative manifest.

Build with:

flatpak-builder --ccache --force-clean build org.gnome.Gtg.json

Run with:

flatpak-builder --run build org.gnome.Gtg.json gtg

Right now is failing with:

$ flatpak-builder --run build org.gnome.Gtg.json gtg 
/app/bin/gtg:54: PyGIWarning: Gdk was imported without specifying a version first. Use gi.require_version('Gdk', '3.0') before import to ensure that the right version gets loaded.
  from gi.repository.Gdk import Screen

(gtg:3): dbind-WARNING **: 08:58:10.314: Couldn't connect to accessibility bus: Failed to connect to socket /tmp/dbus-W9FZd9CTBT: Connection refused
/app/lib/python3.5/site-packages/GTG/gtk/manager.py:22: PyGIWarning: Gtk was imported without specifying a version first. Use gi.require_version('Gtk', '3.0') before import to ensure that the right version gets loaded.
  from gi.repository import GObject, Gtk
Traceback (most recent call last):
  File "<frozen importlib._bootstrap>", line 890, in _find_spec
AttributeError: 'DynamicImporter' object has no attribute 'find_spec'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/app/bin/gtg", line 62, in <module>
    from GTG.gtk.manager import Manager
  File "/app/lib/python3.5/site-packages/GTG/gtk/manager.py", line 26, in <module>
    from GTG.gtk.browser.browser import TaskBrowser
  File "/app/lib/python3.5/site-packages/GTG/gtk/browser/browser.py", line 34, in <module>
    from GTG.gtk.browser.custominfobar import CustomInfoBar
  File "/app/lib/python3.5/site-packages/GTG/gtk/browser/custominfobar.py", line 26, in <module>
    from GTG.tools.networkmanager import is_connection_up
  File "/app/lib/python3.5/site-packages/GTG/tools/networkmanager.py", line 23, in <module>
    from gi.repository import NetworkManager, NMClient
  File "/usr/lib/python3.5/site-packages/gi/importer.py", line 127, in find_module
    'introspection typelib not found' % namespace)
ImportError: cannot import name NetworkManager, introspection typelib not found