do not perform database or keystone setup in nova-compute

- do not perform database or keystone initialization in nova-compute
  image (these should happen in the controller images).
- fix incorrect nova.conf path
- configure keystone_authtoken correct

NB: This still won't result in a working image, because it does not
configure the RPC settings yet.  That will be for a subsequent patch.

Change-Id: Icbd66104ef817d360c46003b29fff63f66ace8d2