* Removes `Synchronous` from the names and descriptions of File I/O as it leaks impl details
* Removes the factries for FileSource and FileSink and puts them in Source and Sink respectively
- explicitly provide Unit values and place parens around tuple creation
- remove structural type usage in TestUtils
- fix Java double-casts
- use unused Java values by asserting their non-nullness
- work around inability to place case class in trait (scripted test)
The remaining warnings about using private types in public methods are
bogus as reported in https://issues.scala-lang.org/browse/SI-9490.
These are synchronous implementations, because we need to be Java 6
compatible while developing on 2.3.x. However asynchronous
implementations using AsynchronousFileChannel will come soon for JDK7
users.
+ ActorPublisher/Subscriber now manage stopping of the actor
+ added documentation on configuring dispatcher for File IO
+ properly handle if source file does not exist
+ file sink / source come with default io dispatcher
> verified no actors are leaking
> exceptions are caught and onErrored properly
+ moved files to akka.stream.io
+ Added OutputStreamSink and InputStreamSource
