Convert unrescue_instance to objects

Related to blueprint icehouse-objects.
Related to blueprint compute-manager-objects.

Change-Id: Id1311064354ee055a3557ce6aafca148c76524ec
Convert add_fixed_ip_to_instance to objects

Related to blueprint icehouse-objects.
Related to blueprint compute-manager-objects.

Change-Id: I2c79b02e20347caaa2c0c67c46c22b818559aceb
Convert remove_fixed_ip_to_instance to objects

Related to blueprint icehouse-objects.
Related to blueprint compute-manager-objects.

Change-Id: I443784d95cf0556dc4e6f9ac7f91466c766819b6
Convert post_live_migration_at_destination to objects

Related to blueprint icehouse-objects.
Related to blueprint compute-manager-objects.

Change-Id: Icaf0346c852d2f6a804675c975e54a7df642c1ab