akka-actor 2.3.0-RC4 and final differ.

The release notes state that akka-actor 2.3.0 will be identical to RC4, but [the news](http://akka.io/news/2014/03/05/akka-2.3.0-released.html) lists differences, as well akka-actor-specific changes in [the comparison between the tags](https://github.com/akka/akka/compare/v2.3.0-RC4...v2.3.0).