Update failed assert text to match code in SizeEstimatorSuite

Author: Jeff Hammerbacher <jeff.hammerbacher@gmail.com>

Closes #3242 from hammer/patch-1 and squashes the following commits:

f88d635 [Jeff Hammerbacher] Update failed assert text to match code in SizeEstimatorSuite

core/src/test/scala/org/apache/spark/util/SizeEstimatorSuite.scala

@@ -118,7 +118,7 @@ class SizeEstimatorSuite
     // TODO: If we sample 100 elements, this should always be 4176 ?
     val estimatedSize = SizeEstimator.estimate(Array.fill(1000)(d1))
     assert(estimatedSize >= 4000, "Estimated size " + estimatedSize + " should be more than 4000")
-    assert(estimatedSize <= 4200, "Estimated size " + estimatedSize + " should be less than 4100")
+    assert(estimatedSize <= 4200, "Estimated size " + estimatedSize + " should be less than 4200")
   }
 
   test("32-bit arch") {