Moved to Scala 2.11/Akka 2.3.8 and SBT + new room

* Migrated to SBT
* Set Scala to 2.11 and fixed issues with case classes inheritance
* Set Akka to 2.3.8 (no issues)
* Added new room (ThePit)
* Read the description of a room upon entering

Please note: the exits for the new room do not seem to be respected, this might reveal a bug in the current codebase.