Trace an async operation with Kamon with OpenTracing support

TraceFuture.scala

def traceFuture[T](name: String)(f: => Future[T]): Future[T] = {
  val spanBuilder = Kamon.tracer.buildSpan("${getClass().getSimpleName}.$name"))
  val newSpan = addDefaultTags(spanBuilder).start()
  val activatedSpan = Kamon.makeActive(newSpan)
  val evaluatedFuture = f.transform(
    r => { newSpan.finish(); r},
    t => { newSpan.finish(); t}
  )(CallingThreadExecutionContext)
  activatedSpan.deactivate()
  evaluatedFuture
}