Make release process easier

[To-om]

Release process should be automated. The steps are:

1. merge release branch (git flow finish release <release number>)
2. update version in version.sbt and ui/package.json
3. generate changelog
4. run unit tests (sbt test)
5. publish to bintray (sbt publish)
6. publish latest package to bintray
7. publish to docker (sbt docker:publish)
8. commit changes (git commit)

This can be achieve with sbt-release.