HTTP/2 Server implementation is Scala and Akka Streams

This implements the basics of an HTTP/2 server using Akka Streams for all the data flow.

All the build is handled by SBT, and using it should be enough to compile and start testing.

Any actual programs that run the server must start with the Jetty ALPN JAR in it's bootclasspath.
Since there are not supported plain-text protocols this wiill cause issue immediately if not taken care of.

Also, it's necessary to have a keystore set-up, even if with a temporary replacement. Tutorials on how to achieve that
are a available in many places.

One simple example application server is included that just serves files in the local directory, which can be run with
`sbt examples/run`

The default application instance can also be debugged using the :debug configuration.