Adding a Voldemort service to consume PUT and DELETE messages from Kafka

Adding a new Store layer to perform Kafka consumption. Includes configuration properties, such that original workflow is unaffected.
replicaBrokers is not meant to be a configurable option, and should be initialized as an empty list. It's a dynamically populated list which stores the possible brokers in which replicas for the current broker exist. It's only used when a leader election is required.