Set objects indirection API in metadata service

Commit Ia12f48227eb2380f5da93313cd4045577d8857c9 introduces objects in
the metadata service.

As metadata service is supposed to be using the
conductor service for it's database access, we also need to set
nova.objects.baseNovaObject.indirection_api global to point to the
conductor API so that the object actions will be done by RPC to
conductor.

Change-Id: I7aae92c0074e72841aa6c654ad0ada25045863b1
Closes-bug: #1268665
Merge "Set objects indirection API in metadata service"