Split Play tests / upgrade non-DB tests to Play 2.3

* Split the DB tests out of play-scala and play-scala and into new tests. There are already several separate DB tests so this makes things more consistent. ebean and anorm shouldn't be treated differently from jpa, slick, etc.
* Download sbt so that Play 2.3 can use it.
* Update the non-DB tests to Play 2.3.0. We will need to update the DB tests too, but that's a big job that can be done separately. I'm going to ask the community if they can help with updating the DB tests.