libvirt: detect the current hypervisor and use that in the domain XML
libvirt: detect the current hypervisor and use that in the domain XML

cheng--zhang/xenopsd,euanh/xenopsd,djs55/xenopsd,koushikcgit/xenopsd,djs55/xenopsd-previous,cheng--zhang/xenopsd,djs55/xenopsd-previous,koushikcgit/xenopsd,koushikcgit/xenopsd,simonjbeaumont/xenopsd,djs55/xenopsd,djs55/xenopsd,cheng--zhang/xenopsd,thomassa/xenopsd,simonjbeaumont/xenopsd,euanh/xenopsd,thomassa/xenopsd,thomassa/xenopsd,djs55/xenopsd-previous,johnelse/xenopsd,simonjbeaumont/xenopsd,johnelse/xenopsd,johnelse/xenopsd,euanh/xenopsd