Add keystonemiddleware

Keystonemiddleware has the auth_token middleware and other
middleware.

Change-Id: Ia1d5f0a7c1945dcd4084e7dbfae0596bb52a5406
Update alembic and SQLAlchemy versions

These changes are required to implement smart comparison of models
with existing tables for Neutron: https://review.openstack.org/96438.

This is also needed for oslo.db.

Change-Id: I31bcc78c5046a0d9ee386a0f0205ff490e14eb76
Update oslo.vmware to version 0.4

The new version will enable integrating oslo.vmware into Nova. It adds
exception types which are needed in Nova and allows completing the
integration with minimal changes and minimal risk of regressions.

Nova blueprint use-oslo-vmware

Change-Id: I0909da73068739f8cf152a67e5807ee8af57ae44
Merge "Update alembic and SQLAlchemy versions"
Merge "Update oslo.vmware to version 0.4"
Merge "Add keystonemiddleware"