Unused nats properties

[wendorf]

proxy and cf-mysql-broker jobs still have nats properties, and manifest-generation yml files still include them, but the release doesn't use nats anymore.

Also, there's no mention in the README that this has changed and that route_registrar needs to be co-located.

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/143997101

The labels on this github issue will be updated when the story is started.

[jpalermo]

We've removed the properties from the spec files but have left them in the manifest generation since they are still required for the routing release.

The routing release prerequisite has been in the readme for 3 months:
https://github.com/cloudfoundry/cf-mysql-release/blob/develop/README.md#prerequisites-1