Move publishing to sbt-ci-release

[SethTisue]

I'd want to do this before cutting a next release (#225)

• https://github.com/olafurpg/sbt-ci-release
• https://travis-ci.com/github/lightbend/scala-logging/settings

[SethTisue]

note that this involves removing the (confusingly similarly named) sbt-release

sbt-ci-release includes sbt-dynver, so we'll need to remove version.sbt