Open sourcing our NGINX HTTP/2 + SPDY code

On April 28, 2016, Cloudflare released HTTP/2 Server Push support for all customers. Today, 50% of sites that use HTTP/2 are served via Cloudflare. The company has also extracted its changes to NGINX and made them available as a patch, allowing both SPDY and HTTP/2 to be supported together with the standard release of NGINX. To configure an NGINX server to support both HTTP/2 and SPDY on the same port, users need to run `./configure --with-http_spdy_module --with-http_v2_module --with-http_ssl_module`. The patch uses ALPN and NPN to advertise the availability of the two protocols. Cloudflare continues to support SPDY and HTTP/2 across all its sites, monitoring the percentage of connections that use SPDY before making a decision on its eventual deprecation.