Revert "Revert "Stop using hpcloud az1-az3 in favor of region-b""

We have the ability to track failure rates better now, so we should
be able to get some good numbers on whether this is terrible or not.

This reverts commit a906e4b52b8bcddfb6b3346885f99c937b87a0df.

Conflicts:
	modules/openstack_project/templates/nodepool/nodepool.yaml.erb

Change-Id: Id9f27f5d4ec8788ea6a4d67fb15aa81cb2e7f1c3
Merge "Revert "Revert "Stop using hpcloud az1-az3 in favor of region-b"""