reorder and clarify some steps

 5. test services by changing your `/etc/hosts`

 6. shutdown original instance:

 6. destroy test instance:

        ssh $INSTANCE shutdown -h +1 'migrating to new server'

        gnt-instance remove $INSTANCE

 7. destroy test instance:

 7. shutdown original instance:

        gnt-instance remove $INSTANCE

        ssh $INSTANCE shutdown -h +1 'migrating to new server'

 8. redo migration as in step 3, 4 and 5:

 8. redo migration as in step 3, 4 and 5

        ./ganeti -v -H $INSTANCE libvirt-import  --ganeti-node $SPARE_NODE --libvirt-host $KVM_HOST --adopt

        ./ganeti -v -H $SPARE_NODE renumber-instance $INSTANCE

 9. final test procedure