Make Swift *_PORT_BASE configurable

DevStack's Swift port defaults changed in the Grizzly cycle, we need to
put it back to complete the upgrade without going through the ring build process.

Change-Id: I30c09839690ad7ba9bb3fdffa3f05aedfc47559e
Merge branch 'nova-api-revert' into dt-test
Merge branch 'openrc-stackenv' into dt-test
Merge branch 'swift-ports' into dt-test