Make add-remote use title from summary
Make add-remote use title from summary

When we add a remote, load the summary from the repository, and
use the title if there is one. This at the same time serves as
(minimal) validation of the repository url.

matthiasclasen/flatpak,amigadave/flatpak,alexlarsson/xdg-app,handsome-feng/flatpak,chergert/xdg-app,amigadave/flatpak,alexlarsson/xdg-app,thiblahute/xdg-app,GeorgesStavracas/flatpak,handsome-feng/flatpak,amigadave/flatpak,alexlarsson/xdg-app,chergert/xdg-app,handsome-feng/flatpak,flatpak/flatpak,matthiasclasen/xdg-app,thiblahute/xdg-app,matthiasclasen/flatpak,GeorgesStavracas/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,GeorgesStavracas/flatpak,chergert/xdg-app,flatpak/flatpak,thiblahute/xdg-app,matthiasclasen/xdg-app,GeorgesStavracas/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/xdg-app,flatpak/flatpak,chergert/xdg-app,amigadave/flatpak,thiblahute/xdg-app,matthiasclasen/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,alexlarsson/xdg-app,matthiasclasen/flatpak,matthiasclasen/xdg-app