Add a knob to tune the batch size of the Reporter

[sclasen]

Anecdotally 200 metrics take 5 sec or more to post, so 500 would take say 15 maybe? If you have 500 metrics and report more than every 15 secs you are hosed?

[mihasya]

The timeout was not accurately represented in 2.1.2.3, 2.1.2.4 fixed this issue and batches of 200+ are going through at a reasonable pace (see #10 for more detailed discussion). Closing.