update scala 2.11.2 and akka 2.3.5

akka 2.3.2 and scala 2.11.0 are so terrible!

http://akka.io/news/2014/05/22/akka-2.3.3-released.html

> If you were using Akka 2.3.2 for Scala 2.11.0 you need to update immediately, because serialization was broken in Scala
Merge pull request #49 from xuwei-k/update-akka-and-scala

update scala 2.11.2 and akka 2.3.5