HTTP Server:
  - Implement HTTP_Router(), a high-performance, simple http framework that only
    routes requests efficiently and allows to handle more than just http 'request'
    events but also 'checkContinue', 'connect', and 'upgrade'
  - Implement HEAD
  - Add documentation
  - http tests: add tests for various usages of new Serve / HTTP_Router
  - Use Greedy() pipelet