Extract the DOM to Drive name, alias and path logic to reusable method

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1120246
Change-Id: I7389dd8960c9c6245148d9191b2bea5a7e9e4a46
Signed-off-by: Martin Sivak <msivak@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/29059
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-by: Francesco Romani <fromani@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/30066