* RootSettings plugin contains settings for root project
* other auto plugins that are meant only for root project depend on RootSettings
* other auto plugins that are meant for every project are enabled by default reducing boilerplate
* deprecates awaitTermination, shutdown and isTerminated
* introduces a terminate-method that returns a Future[Unit]
* introduces a whenTerminated-method that returns a Future[Unit]
* simplifies the implementation by removing blocking constructs
* adds tests for terminate() and whenTerminated
