Build using SBT

Hi all,

I've added the necessary files to build this project using SBT. [SBT](http://www.scala-sbt.org/) is the de facto standard for building Scala projects and has an integrated dependency management and tools for building, testing and packaging projects. There's also a lot of plugins that make specific tasks easy (e.g. [packaging as fat jar](https://github.com/sbt/sbt-assembly), [creating Eclipse](https://github.com/typesafehub/sbteclipse)/[IDEA](https://github.com/mpeltonen/sbt-idea) project files, [automatically formatting code](https://github.com/sbt/sbt-scalariform), [linting Scala code](https://github.com/puffnfresh/wartremover), [continuous compilation and testing](http://www.scala-sbt.org/0.13.1/docs/Getting-Started/Running.html#continuous-build-and-test), ...)
Could you try if building and packaging works as you expect it to (see README) and tell me if you need something more/else?