remove dbus from apparmor profile

This removes the dbus entry from the apparmor profile Docker creates.

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
Merge pull request #4503 from unclejack/attempt_to_fix_apparmor_profile

remove dbus from apparmor profile for Ubuntu 12.04