[SPARK-2570] [SQL] Fix the bug of ClassCastException

Exception thrown when running the example of HiveFromSpark.
Exception in thread "main" java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer
	at scala.runtime.BoxesRunTime.unboxToInt(BoxesRunTime.java:106)
	at org.apache.spark.sql.catalyst.expressions.GenericRow.getInt(Row.scala:145)
	at org.apache.spark.examples.sql.hive.HiveFromSpark$.main(HiveFromSpark.scala:45)
	at org.apache.spark.examples.sql.hive.HiveFromSpark.main(HiveFromSpark.scala)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:303)
	at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:55)
	at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)

Author: Cheng Hao <hao.cheng@intel.com>

Closes #1475 from chenghao-intel/hive_from_spark and squashes the following commits:

d4c0500 [Cheng Hao] Fix the bug of ClassCastException
SPARK-2553. CoGroupedRDD unnecessarily allocates a Tuple2 per dependency...

... per key

My humble opinion is that avoiding allocations in this performance-critical section is worth the extra code.

Author: Sandy Ryza <sandy@cloudera.com>

Closes #1461 from sryza/sandy-spark-2553 and squashes the following commits:

7eaf7f2 [Sandy Ryza] SPARK-2553. CoGroupedRDD unnecessarily allocates a Tuple2 per dependency per key
SPARK-2553. Fix compile error

Author: Sandy Ryza <sandy@cloudera.com>

Closes #1479 from sryza/sandy-spark-2553 and squashes the following commits:

2cb5ed8 [Sandy Ryza] SPARK-2553. Fix compile error