Add XEN to hypervisor list for VPC

Signed-off-by: David Scott <dave.scott@citrix.com>
Add XEN to hypervisor.list and system.vm.default.hypervisor

Signed-off-by: David Scott <dave.scott@citrix.com>
XEN: implement getHostVmStateReport()

This function already has a switch/case between LXC and KVM.

Signed-off-by: David Scott <dave.scott@citrix.com>
ui: set the default disk type to QCOW2 for both XEN and KVM

Signed-off-by: David Scott <dave.scott@citrix.com>
make the system VM template unique

Signed-off-by: David Scott <dave.scott@citrix.com>
XEN: add more default configuration for the new hypervisorType

Signed-off-by: David Scott <dave.scott@citrix.com>