Set spark.deploy.spreadOut to true by default in 0.7 (improves locality)

core/src/main/scala/spark/deploy/master/Master.scala

@@ -43,7 +43,7 @@ private[spark] class Master(ip: String, port: Int, webUiPort: Int) extends Actor
   // As a temporary workaround before better ways of configuring memory, we allow users to set
   // a flag that will perform round-robin scheduling across the nodes (spreading out each app
   // among all the nodes) instead of trying to consolidate each app onto a small # of nodes.
-  val spreadOutApps = System.getProperty("spark.deploy.spreadOut", "false").toBoolean
+  val spreadOutApps = System.getProperty("spark.deploy.spreadOut", "true").toBoolean
 
   override def preStart() {
     logInfo("Starting Spark master at spark://" + ip + ":" + port)