Session address is saved to /var/run/dbus/session_bus_address, which is read
in /etc/profile.d/dbus-session-address for interactive login and by adbd for
applications launched from QtCreator.

Change-Id: I8e1f43bdb2f7a7b0450dacf39890cf149459bbf4
Reviewed-by: Rainer Keller <rainer.keller@theqtcompany.com>