Add a SparkDDLTask for Shark-specific metastore operations.
Includes support for ALTER TABLE <old naem> RENAME TO <new name>.

Currently, this is meant to be a dependent task on Hive's DDLTask.
Unit test for ALTER TABLE RENAME TO on cached tables.
Fix merge mistake in SharkDDLSemanticAnalyzer.
Make SparkDDLTask#alterTable() more general.

+ Only create a SparkDDLTask for cached table ops.
Merge pull request #181 from harveyfeng/spark-ddl-task

Add a SparkDDLTask for handling Shark-specific metastore operations.
SparkDDLTask(Work) => SharkDDLTask(Work)
Set Shark version to 0.9.0-SNAPSHOT and use Spark's master branch version, 0.9.0-incubating-SNAPSHOT
Merge pull request #183 from harveyfeng/rename-ddl

SparkDDLTask(Work) => SharkDDLTask(Work)
Merge pull request #184 from harveyfeng/patch-1

Set Shark version to 0.9 and use Spark 0.9/master (incubating)
Add a NULL check in ReduceKeyReduceSide#equals().
Revert to using RDD#collect() for map joins,
Since Spark can send Task results through the block manager when the Akka frame size is exceeded

- Reverts Shark PR #98
- Relevant commit on the Spark side: apache/incubator-spark@c75eb14
Merge pull request #187 from harveyfeng/mj-bug-swat

Revert to using RDD#collect() for map joins,
Get Shark to compile with latest Spark master.
Merge remote-tracking branch 'ampshark/master'
Remove Kryo references in SharkEnv. The ShuffleSerializer is explicitly specified as the object serializer for shuffle ops.
Merge pull request #189 from harveyfeng/master

Get Shark to compile with latest Spark master.