Replace this with
```
@transient lazy val ser: SparkKryoSerializer = {
  val sparkConf = Option(SparkEnv.get).map(_.conf).getOrElse(new SparkConf())
  new SparkKryoSerializer(sparkConf)
}
```
So that SparkConfs don't get initialized twice in the master. We can also remove all the `initWith...` methods (and references in SharkEnv, SerializationSuite, etc).