This entails:
* adding akka.pattern.PatternCS.* to enable ask etc. with
CompletionStage
* changing RequestContext to offer an ExecutionContextExecutor for the
CompletionStage.*Async combinators
* splitting up akka.stream.Queue for JavaDSL consistency
* remove settings duplication between AkkaBuild and project specific .sbt files
* do not publish test projects
* run akka-http-core tests
* fix lambda sample project versions
* remove obsolete projects (streamAndHttp, httpParent, docsDev)
* exclude parsing project from unidoc
* update to the latest sbt