engine,webadmin: Show VM as stateless in audit log

Show different message in audit log (Events), in case a VM
was started in stateless mode
(can be specified in RunOnce dialog - 'stateless' checkbox option or
in Edit VM dialog (for desktop only).

Change-Id: Id9bb0bd88e544880406c340afb7e213041b2f845
Bug-Url: https://bugzilla.redhat.com/907997
Signed-off-by: Libor Spevak <lspevak@redhat.com>