SPARK-1109 wrong API docs for pyspark map function

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes apache#73 from ScrapCodes/SPARK-1109/wrong-API-docs and squashes the following commits:

1a55b58 [Prashant Sharma] SPARK-1109 wrong API docs for pyspark map function

python/pyspark/rdd.py

@@ -163,7 +163,7 @@ def getCheckpointFile(self):
 
     def map(self, f, preservesPartitioning=False):
         """
-        Return a new RDD containing the distinct elements in this RDD.
+        Return a new RDD by applying a function to each element of this RDD.
         """
         def func(split, iterator): return imap(f, iterator)
         return PipelinedRDD(self, func, preservesPartitioning)