Set vm_state to ERROR on net deallocate failure.

If deallocate_network_for_instance from network.api fails while trying
to terminate an instance, set the vm_state to ERROR.  Previously it
still completely failed at this point, but the instance vm_state was
still ACTIVE but the task_state was stuck in deleting.  Now it will be
ERROR/deleting.

Fix bug 1110221.

Change-Id: I181a11c8de667fa462e1a2cb75b2c8ae41410273
Merge "Set vm_state to ERROR on net deallocate failure."