Add a custom task and dependency to compile .pyc files and install them in the jarfile artifact

package_pyc_in_jar_fragment.sbt

lazy val compilePython = taskKey[Unit]("Compile python files")

compilePython := {
  val s: TaskStreams = streams.value
  s.log.info("compiling python...")
  val stat = (Seq("python2", "-m", "compileall", "python/") !)
  if (stat == 0) {
    s.log.info("python compile succeeded")
  } else {
    throw new IllegalStateException("python compile failed")
  }
}

(packageBin in Compile) <<= (packageBin in Compile).dependsOn(compilePython)

mappings in (Compile, packageBin) ++= Seq(
  (baseDirectory.value / "python" / "isarnproject" / "__init__.pyc") -> "isarnproject/__init__.pyc",
  (baseDirectory.value / "python" / "isarnproject" / "sketches" / "__init__.pyc") -> "isarnproject/sketches/__init__.pyc",
  (baseDirectory.value / "python" / "isarnproject" / "sketches" / "udaf" / "__init__.pyc") -> "isarnproject/sketches/udaf/__init__.pyc",
  (baseDirectory.value / "python" / "isarnproject" / "sketches" / "udaf" / "tdigest.pyc") -> "isarnproject/sketches/udaf/tdigest.pyc",
  (baseDirectory.value / "python" / "isarnproject" / "sketches" / "udt" / "__init__.pyc") -> "isarnproject/sketches/udt/__init__.pyc",
  (baseDirectory.value / "python" / "isarnproject" / "sketches" / "udt" / "tdigest.pyc") -> "isarnproject/sketches/udt/tdigest.pyc"
)