!str #15705 Update to Akka 2.3.5, and new akka-persistent api

* 2.3.5 dependency
* PersistentPublisher is using PersistentView, and is producing the
  raw events instead of the Persistent wrappers
Merge pull request #15720 from akka/wip-15705-stream-dependency-akka-2.3.5-patriknw

!str #15705 Update to Akka 2.3.5, and new akka-persistent api