Add batched event processing to Java client

This PR creates event processing scaffolding and publishes feature request events to LaunchDarkly. 
Here it is, hopefully it is equivalent: https://github.com/launchdarkly/gonfalon/commit/66466ee33d88764cc32cf3845c93853c7f9ce696#diff-99275a897680eec628d77bbf2cb3c112R264