MesosClusterScheduler generate bad command options

desc.schedulerProperties
      .filter { case (key, _) => !replicatedOptionsBlacklist.contains(key) }
      .foreach { case (key, value) => options ++= Seq("--conf", s"$key=${shellEscape(value)}") }
    options

As above, --conf option value is not enclosed by "", for example, if we have a multi value config like

spark.driver.extraJavaOptions= -Dlog4j.configuration=file:./conf/log4j-server.properties -Dalluxio.user.file.writetype.default=THROUGH

Without "" the next alluxio config will be treated as spark-submit options and cause error.