Dispatch Reboot

A rethink of Dispatch with sonatype/async-http-client as the underlying transport library.

Currently, you can do something like this:

import dispatch._
val raw = :/("raw.github.com").secure
val readme = raw / "dispatch" / "reboot" / "master" / "README.markdown"
val promise = Http(readme > As.string)
for (string <- promise) {
  println(string)
}

// tidy up
Http.shutdown()