Release skinny-logback without scala-lang deps

skinny-logback 1.0.0 is already available on the sonatype repository.  

We found an issue with scoverage too. https://github.com/scoverage/sbt-scoverage/issues/57

Good article by @xerial helped me a lot. Thanks. http://xerial.org/blog/2014/03/24/sbt/