Out of Socket error when bulk inserting

[polyfractal]

Ran into a drastic performance problem. Sherlock is using the Guzzle class incorrectly, creating a new Client() for each request. I assumed that Guzzle shares curl handles across Clients(), but this is not actually true.

As a result, bulk inserts tend to deplete the system of sockets very quickly, causing the entire process to fail.

Need to split the Client initialization into its own class, similar to the Cluster class, so that it may be shared.

Related, I'm going to try some experiments with Rolling-Curl (https://github.com/chuyskywalker/rolling-curl), which I think has a better batch/streaming mode of executing multi-handles