Implement standalone mode for test.

There is no need to launch zookeepr for test. And restarting zookeeper
server for every test makes test slow.

This patch implements the option to launch standalone mode. The
standalone mode will not make routing table so it doesn't need to launch
zookeeper.
The name of the method is already `launchZooKeeperServerIfNecessary`, so how about check `BeyondConfiguration.isStandaloneMode` inside the method?