This commit changes the structure of Verspaetung pretty dramatically to allow
for the registering of Gauges for the various offsets
With this change the KafkaPoller is pushing the latest offsets into a map and the
ZK consumer tree watchers are pushing consumer offsets into a separate map.
References #17
This commit includes a lot of work in progress kind of code. STill
experimenting with how to bind the events from the Zookeeper event-driven
system, in with the KafkaPoller busy-wait-loop system.