Require latest flatpak (2017.5)
Require latest flatpak (2017.5)

This allows us to rely on the new BARE_USER_ONLY mode, as
well as the fixes to progress reporting. Also, it has a lot
of bugfixes that are nice. If you need an old ostree you can
run the old flatpak series.

handsome-feng/flatpak,flatpak/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,flatpak/flatpak,handsome-feng/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,flatpak/flatpak,GeorgesStavracas/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,flatpak/flatpak,handsome-feng/flatpak