Fix for compile error, and bump to 2.6

This turned into a yak shaving exercise.  The end result might not be what we want.

My objective was to just to build Machine for 2.6 on Scala 2.9 and Scala 2.10 (with SBT 0.13, but that's not very interesting). I made the changes, fixed the deprecations and then ran into issue #2.  

Issue 2 has a fix (from line 259 of _ProtoStateMachine.scala_). But I was uncomfortable that there are no unit tests. 

So I added a unit test, _TransitionSpec.scala_, using an in-memory database, using the nice `Around` facilities in Specs2. That was all good, but when I ran `+test` I remembered that Spec2 changed the way it handles `Around` between library versions for Scala 2.9.2 and 2.10. (For Scala 2.9 Specs2 is version 1.12.xx and for Scala 2.10 it is at 2.3.x).

I didn't see an obvious way to hide the differences. Nor was I sure it's worth that much effort.

So in the second commit I in-lined the in-memory database set up in the unit test, and it runs for 2.9 and 2.10.  

Not great, but not sure what else to do here.