update deallocate_for_instance to take instance obj

Update the deallocate_for_instance() method of the nova.network rpc API
to take a full instance object instead of just an instance UUID and some
other instance data.  This patch is just the mechanics of getting the
API changed.  The next patch will make use of getting the full instance
object to eliminate a db query in nova-network.

Part of blueprint nova-network-objects

Change-Id: I9be88206ecc64a92d2826a9ac43e4d2d384f29ff
Merge "update deallocate_for_instance to take instance obj"