Merge pull request #583 from colorant/zookeeper.

Minor fix for ZooKeeperPersistenceEngine to use configured working dir

Author: Raymond Liu <raymond.liu@intel.com>

Closes #583 and squashes the following commits:

91b0609 [Raymond Liu] Minor fix for ZooKeeperPersistenceEngine to use configured working dir

(cherry picked from commit 68b2c0d)
Signed-off-by: Aaron Davidson <aaron@databricks.com>

Conflicts:
	core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperPersistenceEngine.scala

core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperPersistenceEngine.scala

@@ -77,7 +77,7 @@ class ZooKeeperPersistenceEngine(serialization: Serialization)
   }
 
   def deserializeFromFile[T <: Serializable](filename: String)(implicit m: Manifest[T]): T = {
-    val fileData = zk.getData("/spark/master_status/" + filename)
+    val fileData = zk.getData(WORKING_DIR + "/" + filename)
     val clazz = m.erasure.asInstanceOf[Class[T]]
     val serializer = serialization.serializerFor(clazz)
     serializer.fromBinary(fileData).asInstanceOf[T]