Adding kvm-block-migration feature. 
Adding kvm-block-migration feature. 

I wrote some description the below URL. I hope it may help for reviewing.
<http://etherpad.openstack.org/kvm-block-migration>
openstack-attic/melange,rackerlabs/melange,openstack-attic/melange,openstack-attic/melange,rajarammallya/melange,rackerlabs/melange,rajarammallya/melange,rajarammallya/melange,rackerlabs/melange