Http stream end to end tests

[ejizba]

These tests include:

• A "hello world" request with "transfer-encoding" set to "chunked" (the default for any streamed request)
• Streaming random data up to 2g in both the request and the response
• 256 concurrent requests

These tests are not meant to be exhaustive performance/stress testing and do not represent the limits of what the feature can do, just the limits of what I wanted to included in our end-to-end tests. I still want separate perf testing

I'm still testing streaming both on and off, with the former as the default and the latter as a part of the "oldConfig" test pass.