[Sprint: 38] XD-2339a KafkaConsumer configs as module options

 - Remove external config properties for kafka consumer
 - Add module options for all the possible kafka consumer configurations
Also, the value used to be "smallest" prior to 0.8, and it's been changed, in order to accomodate migration from 0.7 to 0.8 - I don't think that motivation applies to us.