vdsm: Report fake capabilities

This patch introduces a 'fake KVM on PPC64' mode, adding
a configuration parameter indicating to VDSM if it must report fake
capabilities, so a x86_64 host could be used to validate PPC64-specific
code.

Change-Id: Ifb934eb8aff1ac0ce82ea5d5bd082afce6d9ba50
Signed-off-by: Vitor de Lima <vitor.lima@eldorado.org.br>
Reviewed-on: http://gerrit.ovirt.org/19396
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>