The session list is supposed to hide itself if
1) the user is already logged in
2) there is only one xsession file installed
There was a bug causing 2) not to work.
This commit fixes that bug.
https://bugzilla.gnome.org/show_bug.cgi?id=658423
This commit adds GDM session support.
It provides a user list that talks to GDM,
handles authentication via PAM, etc.
It doesn't currently support fingerprint readers
and smartcards.
https://bugzilla.gnome.org/show_bug.cgi?id=657082
