Add a SparkLoadWork, SparkLoadTask for supporting LOAD DATA INTO for cached tables.
Add a util method that directly launches a task which alters the
SerDe property of a table or table partition.
Merge branch 'master' into unified-load

Conflicts:
	src/main/scala/shark/parse/SharkDDLSemanticAnalyzer.scala
	src/main/scala/shark/parse/SharkSemanticAnalyzerFactory.scala
Tests for HiveUtils methods that alter table/partition SerDe.
Take optional HiveConf (meant to reflect a session state) in HiveUtils metastore helpers.
A few small comments for SharkSemanticAnalyzer.
Add a helper function in HiveUtils that creates a UnionOI for a schema that includes partitioned columns.
Hive compliance: pass a NULL partition specification in HiveUtils#alterSerDeInHive() helper.

This indicates a non-partitioned table, and makes it slightly easier to deal with
NULLs/Options in the code.
New method in Utils that creates a PathFilter based on the snapshot of a given path.

Useful in computing deltas (i.e., new files/directories) for HadoopRDD loads.
Add `unifyView` fields in Shark Tables.
Enable deserializer specification in HadoopTableReader.

The default would be the deserializer specified by the table
descriptor.
One case for which a different deserializer is specified is
for updates to a unified view. The table descriptor's deserializer
is a ColumnarSerDe, so a deserialize()-capable disk/Hadoop deserializer
is passed directly to makeRDDForTable() or makeRDDForPartitionedTable().
Add fields to Table and PartitionedMemoryTable to track SerDes,
for deserialize()-ing disk reads.
Account for unified views in Shark table creation in MemoryMetadataManager.
Additions to SparkLoadTask and SparkLoadSemanticAnalyzer to
support CTAS, INSERT INTO, INSERT OVERWRITE, LOAD INTO and
LOAD OVERWRITE.
Initial implementation for semantic analysis of unified views.
Misc cleanup/adjustments from unified view changes.
Alter SerDes for regular CREATE TABLE commands for tables with unified views.

The SharkDDLTask alters the SerDe by creating an launching a Hive DDLTask.
This breaks Hive abstraction, but is much simpler to implement...
Flatten both RDD arguments for RDDUtils#unionAndFlatten()
Non-working version of table persistence.
Comment about the unify view creation in SharkDDLTask.