Merge http2-protocol into http2

OK, here we have a PR that fixes #77 *and* #78, and bumps the version to 3.0.0 because of API incompatibility.

Tests pass, and I can use this to test Firefox, as well (with a few modifications in mozilla-central to change to the new API).

The vast majority of this PR is a giant slurping in of the stuff from node-http2-protocol (I opted to lose history for those files, since the incantations to keep history are ugly in the extreme, and we'll always have the old repos around for historical purposes, anyway.) The rest is changing the API to the one we discussed in #78, and minor tweaks to make everything nicer.

I figured it'd be good to get a second set of eyes to look this over, since it's pretty invasive, so @molnarg, can you take a look?