Fixed Akka logging config

In Akka 2.2 'event-handlers' is a deprecated config.
Fixed typo in migration guide for Play 2.2
Merge pull request #1484 from corruptmemory/fix-akka-logging-config

Fixed Akka logging config
Merge pull request #1485 from corruptmemory/fix-doc-typo

Fixed typo in migration guide for Play 2.2