Disable Login User List on Fedora 21

With the new version of Gnome 3 on Fedora 21, previous methods of disabling the user list in the gdm login no longer seems to work.
Now you have to edit configuration database with the gsettings command as the gdm user.

Type in the following command to set the disable-user-list option to true in the gdm user’s copy of the dconf database

sudo -u gdm gsettings set org.gnome.login-screen disable-user-list true

Follow that up with a restart of the gdm service to apply the new setting.

systemctl restart gdm