Replication for scalability

Multiple instances of `whodis` should be able to run as a cluster, with a query to an instance being rerouted to the appropriate instance which has value for the key.

This issue involves:
1. writing code to read a config file with a list of replicas, and ensuring that each replica has an identical view of the cluster
2. modifying the "write" and "read" code to determine which replica should be servicing the request, and forwarding the request to the appropriate one

Hint: the hash space can be split equally between replicas by taking the hash of the key modulo no. of replicas

PS: Partial implementation still counts!