RailsStatsPublisher doesn't work with pipelines

[kule]

Within a Jenkinsfile running:

    step([
      $class: "RailsStatsPublisher",
      rakeInstallation: "",
      rakeWorkingDir: ""
    ])

gives:

java.lang.UnsupportedOperationException: no known implementation of interface jenkins.tasks.SimpleBuildStep is named RailsStatsPublisher

I assume that the railsStats code will need some similar amendments as were made to the rcov/saikuro tasks in: #28