Changes to work with kafka 0.8

These changes are based on an initial set of changes from clippPR to get the river to work with Kafka 0.8.  I made a few changes based on the changes to the consumer offset being logical vs. physical as well as some subtle changes to the differences in exception handling between 0.7 and 0.8.  Also made a fix for the case where connection issues occur in the dumpStats utility method so that the river will reconnect.  One final change was to add a new river configuration param named 'startFromNewestOffset' (defaults to false) which allows you to configure the river to start either from the oldest or newest offset.