[SPARK-2151] Recognize memory format for spark-submit

int format expected for input memory parameter when spark-submit is invoked in standalone cluster mode. Make it consistent with rest of Spark.

Author: nravi <nravi@c1704.halxg.cloudera.com>

Closes #1095 from nishkamravi2/master and squashes the following commits:

2b630f9 [nravi] Accept memory input as "30g", "512M" instead of an int value, to be consistent with rest of Spark
3bf8fad [nravi] Merge branch 'master' of https://github.com/apache/spark
5423a03 [nravi] Merge branch 'master' of https://github.com/apache/spark
eb663ca [nravi] Merge branch 'master' of https://github.com/apache/spark
df2aeb1 [nravi] Improved fix for ConcurrentModificationIssue (Spark-1097, Hadoop-10456)
6b840f0 [nravi] Undo the fix for SPARK-1758 (the problem is fixed)
5108700 [nravi] Fix in Spark for the Concurrent thread modification issue (SPARK-1097, HADOOP-10456)
681b36f [nravi] Fix for SPARK-1758: failing test org.apache.spark.JavaAPISuite.wholeTextFiles

core/src/main/scala/org/apache/spark/deploy/ClientArguments.scala

@@ -21,6 +21,8 @@ import scala.collection.mutable.ListBuffer
 
 import org.apache.log4j.Level
 
+import org.apache.spark.util.MemoryParam
+
 /**
  * Command-line parser for the driver client.
  */
@@ -51,8 +53,8 @@ private[spark] class ClientArguments(args: Array[String]) {
       cores = value.toInt
       parse(tail)
 
-    case ("--memory" | "-m") :: value :: tail =>
-      memory = value.toInt
+    case ("--memory" | "-m") :: MemoryParam(value) :: tail =>
+      memory = value
       parse(tail)
 
     case ("--supervise" | "-s") :: tail =>