[freyes,r=wolsen,hopem] Add option for a single nova-consoleauth instance.
Introduces a new configuration option for ensuring that only a single nova-consoleauth
daemon is running within the nova-cloud-controller cluster. This allows a deployment
which does not pair with a shared key/value store for auth tokens (e.g. memcached) to
serve consistent authtokens for console access.
Closes-Bug: #1418597