vdsm: Accents in the vm name break the migration

Added utf-8 encoding of the configuration xml on the destination to
handle non-ascii characters.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1002246
Change-Id: I9db5ea4f0745ef42633e3d265bcf40fb4733b2ce
Signed-off-by: Martin Betak <mbetak@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/19684
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-by: Michal Skrivanek <michal.skrivanek@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>