In a fairly hack and slash fashion, remove the installation of placement
from the nova install docs. Placement will have its own installation
docs.
Configuring access to placement from the controller and compute nodes is
still described.
The depends-on is to the patch that provides placement install docs.
The output of 'nova-status upgrade check' is updated to reflect the
current state of the output of that command; this means it now
includes a fair bit more than checking cells v2 and the existence
of the placement API.
Depends-On: https://review.openstack.org/#/c/628220/
Change-Id: I9e082a9c6d4b6369f1ec6c17bbd3ccc417a5e97b
f21b07153d