V0.10 compat

Note the last bullet in the tl;dr section [on the streams2 blog post](http://blog.nodejs.org/2012/12/20/streams2/).

This makes sure that doesn't ever happen.  All tests pass on v0.10.0.

Also in this pull req, is support for setting `NODE_DEBUG=request` and getting a bunch of debugging output.  I figured since I could not have tracked down the problem without that, it was probably worth leaving in.  (We use that env in core for this purpose.)