Fix the rest of direct uses of instance module objects

This switches the remaining occurences of
nova.objects.instance.Instance* to nova.objects.Instance*.

Partial-Blueprint: object-subclassing

Change-Id: I3017c149cc9fbc6b1fbecb003dc55455b1dcd12c
Fix object code direct use of other object modules

The object code itself should not explicitly reference its own objects,
as objects could be subclassed.

Also: There were a few objects that had their own __init__()s that
didn't support accepting 'context' or kwargs. At some point here, we
should also require that context is passed when instantiating the
objects. So, I added the (currently optional) context argument on some
object instantiations near the places I was touching.

Partial-Blueprint: object-subclassing

Change-Id: Icf631c770e347b4bb32999c4ba2431d1db49e11c
Make Evacuate API use Instance objects.

Replace current instance dicts and conversions to Instance Objects.
Add services arg to create_fake_instance_obj.

Change-Id: I7ddf11ce17df254a8253461e17b5c6519cb7d6fe
Related to blueprint compute-manager-objects-juno
Merge "Fix the rest of direct uses of instance module objects"
Merge "Fix object code direct use of other object modules"
Merge "Make Evacuate API use Instance objects."