data: rename gnome-shell required component to org.gnome.Shell

gnome-shell is now dbus activated. The new name is org.gnome.Shell.

https://bugzilla.gnome.org/show_bug.cgi?id=760386

data/gnome-classic.session.desktop.in.in

 [GNOME Session]
 _Name=GNOME Classic
-RequiredComponents=gnome-shell;gnome-settings-daemon;nautilus-classic;
+RequiredComponents=org.gnome.Shell;gnome-settings-daemon;nautilus-classic;