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!
FYI scalatest asserts are a type of matchers. But anyway that seems reasonable to me. My preference is for asserts since there is just one style and it should cover ever use case. but no particular backing as to them being better...