[packagekit] DBus Insterface of G_TYPE_STRV

[Tick]

Hi Richard,
    I found that recently InstallPackage becomes *InstallPackages* and 
the dbus interface becomes
from G_TYPE_STRING to G_TYPE_STRV.  (I can use DBUS_TYPE_STRING originally)

Because of G_TYPE_DBUS is not a basic dbus type (it from dbus-glib.h), 
it becomes very nasty for me to create a G_TYPE_STRV with basic dbus type. 

* Is that possible to keep the original interface such as "InstallPacakge".

UpdatePackage, and RemovePacakge  as well.

Cheers,
Tick