kvm: During migrate change the VNC listen address

The migrate method from libvirt supports passing down a different XML for running
the instance of the target hypervisor.

This enables the VNC to bind to the private IP Address of the hypervisor and during
migration this will be changed to the private IP address of the target host.

This way VNC doesn't listen world wide and is much safer.
CLOUDSTACK: 4640 - Fixed indentation issues in function createInstance
CLOUDSTACK: 4635 - Fixed test case issues due to wrong indentation
CLOUDSTACK-4634: Fixed issue arising due to wrong indentation