implement batch get service

[haifeiWu]

implement batch get service

[thrawn01]

We shouldn't change the interface, we should instead have the standard interface batch many requests to the same machine if they all come in around the same time. We do this in gubernator which you can see here. https://github.com/mailgun/gubernator/blob/master/peer_client.go#L272-L312

Additionally this feature should be optional, as batching requests means we are trading latency for throughput and some users might care more about latency.

[haifeiWu]

Ok, let me change the way of implementation

[thrawn01]

closing due to age