HTTP2 in DoneJS

[matthewp]

A blog post announcing the release of HTTP2 support in DoneJS. This will include:

• done-serve sets up an HTTP2 server if --key and --cert are provided (HTTP2 requires SSL).
• done-ssr using PUSH on assets when in an HTTP2 server (note, this is currently only turned on for the incremental renderer, we can make it optional for the traditional renderer).
• Integration with steal-push maybe? (not implemented yet).
  • Note that this can benefit HTTP1 as well by adding Preload headers (supported in Chrome and Safari (issue))
• A little about incremental rendering and what it is (or should this be a separate post by itself?)

Note that I would like this to be a post about the features, not a guide. Perhaps there should be mini-guides about each feature and link to them from the blog post.

[matthewp]

cc @chasenlehara @justinbmeyer what do you think about this?