Add support for building Scala-based plugins

Introduce support for the first Gerrit plugin written in Scala
and for potentially other future plugins.

Change-Id: I32bcc0640854dfea01617e8408708b985d863dc1
7 files changed
tree: 556468905af15d8810b31f4006a4b74d517f2344
  1. jenkins/
  2. jenkins-docker/
  3. .gitignore