(TK-108) Add support for persistent Java clients

This PR adds support for both synchronous and asynchronous persistent Java clients.
Ah, I see. I was a little confused by the Logger stuff, as I noticed while writing this that, as the code currently stands in master, `AsyncHttpClient`, `SyncHttpClient`, and `SslUtils` all have loggers for the `SyncHttpClient` class, and I was unsure if that was intentional or not.