Deployment of the nodepool cloud.yaml file is currently failing with
FAILED! => {"changed": false, "msg": "AnsibleUndefinedVariable: 'rackspace_username' is undefined"}
This is because the variables in the group_vars on bridge.o.o are all
prefixed with "nodepool_". Switch to this.
Change-Id: I524cc628138d85e3a31c216d04e4f49bcfaaa4a8
a7e85e75b1