Validate the offset received from kafka when consuming
Only update the stored offset on successful events
Only disconnect the broker on error conditions

Otherwise we pull it out from underneath other producers/consumers who might be
talking to it.
Merge pull request #119 from Shopify/validate-offset

Validate the offset received from kafka when consuming
Merge pull request #120 from Shopify/leave-broker-connected

Only disconnect the broker on error conditions
first round debugging info
moar debug
moar debug