FileTailSource and DirectoryChanges have moved to Alpakka

[ennru]

FileTailSource and DirectoryChanges are part of Alpakka now.

See

• https://developer.lightbend.com/docs/alpakka/current/file.html#tailing-a-file-into-a-stream
• https://developer.lightbend.com/docs/alpakka/current/file.html#listening-to-changes-in-a-directory

They should be removed from this repository.

[ennru]

Let's deprecate them in 0.10 and remove the sources some later release.