Support overriding Zookeeper connector to production via env property

This will allow to run production connector (and no stub runner) without `prod` profile (e.g. under `dev`) if `microservice.production` is defined
We came to conclusion that `standalone` and `inMemory` are better names than `production` and `testing`. Can you change your condition names and as well as `productionZookeeperConnector()` and `testingZookeeperConnector()` to above? I know you were just following conventions :-).