Commit 6db42a6 updated heat's keystone auth middleware to support
keystone v3, however heat fails to operate with this configuration in
place. This commit reverts this particular part of commit 6db42a6 to
to restore heat functionality.
Additionally, heat requires auth_uri to contain /v2.0, which is a
non-standard as far as the other projects are concerned.
Change-Id: I52c995e801660e21479a843b4e5410b7e3d349e1
Closes-Bug: #1445402
deaf440546