Move Scalding to 2.10/2.11

So this is just the beginning, but it's a big chunk of the work. I've been doing it between other things.

The big things I've done are to get scalding-core and scalding-hadoop-test working. Note: the DistributedCache tests in scalding-core had a dependency on mockito.... for now I commented it out. Do we want to depend on mockito just for one test? That said, rewriting is going to be a slight pain. So I'm not sure what we want to do there.

Either way, this is to get the ball rolling. I haven't started the 2.11 work becasue we need a new algebird release...but the scalatest migration stuff is enough for the time being!
I was hoping to enlist the compiler in helping with this... can't do that until we're on 2.11 (ie algebird release).  see: https://github.com/twitter/algebird/issues/351