Add release and publish support

[tdauth]

Some links:

• https://github.com/sbt/sbt-release
• https://github.com/verizon/sbt-rig
• https://github.com/scalacenter/sbt-release-early
• http://timperrett.com/2016/10/02/continuous-delivery-for-scala-with-travisci/
• https://central.sonatype.org/
• https://stackoverflow.com/questions/42514143/how-can-i-publish-a-snapshot-artifact-using-sbt-release

Commands sbt release and sbt publish.

Other retest artifacts are released and published this way: https://github.com/retest/recheck/blob/master/pom.xml

With #1 it is not that important to provide releases/publish them online since the REST service can just be deployed and run on a separate machine.

[tdauth]

Seems to work with the ReTest Nexus.