Announcing branch with SPDY support

[Alek Storm]

I've created a branch (https://github.com/alekstorm/tornado/tree/spdy) that implements SPDYv2 support. If you're not excited about SPDY yet, I recommend reading Google's whitepaper (http://dev.chromium.org/spdy/spdy-whitepaper) and the specification (http://dev.chromium.org/spdy/spdy-protocol/spdy-protocol-draft2). To my knowledge, this patch makes Tornado the first Python web framework to support SPDY, and the second web framework in any language to support pushed streams (Node.js is the other).

For more details, see the pull request (https://github.com/facebook/tornado/pull/525), and for even more, see the commit message (https://github.com/alekstorm/tornado/commit/d29d3669a37c8a69635c4ef05851616b0bbfaf76). Since the patch introduces some incompatibilities with current Tornado 2.x applications, it shouldn't be applied until 3.0. Until then, I'll maintain it as a separate branch, with bug reports and other issues welcome.

I'd love to hear any feedback you guys may have.

Alek