[gnome-session] (3 commits) Non-fast-forward update to branch wip/laney/systemd-user-switch

[Iain Lane <iainl src gnome org>]

The branch 'wip/laney/systemd-user-switch' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  c0d43dc... Add a gnome-session-systemd binary to launch the session
  7f4fa89... Add systemd user units
  8db5b9d... Launch sessions with systemd --user.

Commits added to the branch:

  142592d... Add a gnome-session-systemd binary to launch the session
  215e654... Add systemd user units
  26eabb9... Launch sessions with systemd --user.