Fix pep H402 and H401 errors

This is an effort to get the pep ignores to be closer to nova.

Change-Id: I451df579bbead00a8ff2c301c1a84e7c0a896002
Fix pep H306 (import order)

Also remove some unused imports

This is an effort to get the pep ignores to be closer to nova.

Change-Id: I35612de45084fac0ae1c96dad84bb23cfade0e4f
Rename tools/pip-requires to requirements.txt

(and tools/test-requires to test-requirements.txt).

Requested by infra: bug 1179008

Change-Id: I7a6375622d095a9eda232ed82d167fc3a198ed06
Merge "Fix pep H402 and H401 errors"
Merge "Fix pep H306 (import order)"
Migrate to pbr.

Fixes bug 1179007.

Change-Id: Ie921a710d9460196ed8023ad63f05dec998b60f0