Support for Play 2.9 and Play 3.0

[mattclark-zerogravit]

I'm maintaining a repo that uses play-refined. We are currently upgrading from play 2.8 to play 3.0 and this library doesn't have an upgrade path to either play 2.9 or play 3.0. I have forked this repo and have managed to get a version of your codebase working which supports play 2.8, 2.9 & 3.0

The readme has 0.x.0 as if the PR was approved it would need the actual version build adding.

As part of this we dropped support for Scala 2.12 and bumped the version of refined and sbt

There are a lot of changes in the PR but we had problems getting it all to work individually