Merge pull request #234 from harveyfeng/serialization

Fix SerializationSuite failures due to SharkContext NPE
Accept v0.8.0 CacheType enum names.
Merge pull request #236 from harveyfeng/master

Accept v0.8.0 CacheType enum names.
Patches for partition stats and pruning
Tachyon support

Includes
- LOAD, INSERT, ALTER commands already supported on
  heap tables
- Partitioned tables
Test suite for Tachyon support
Upgrade Spark API.
Merge pull request #238 from rxin/upgrade

Upgrade Spark API.
add script support for shark with spark on yarn.
Merge remote-tracking branch 'upstream/master'
Merge pull request #239 from ChengXiangLi/master

add script support for shark with spark on yarn.
Remove extraneous line in TachyonUtilImpl
Merge pull request #237 from harveyfeng/tachyon-support

Tachyon support
Merge branch 'master' into part-stats

Conflicts:
	src/main/scala/shark/execution/MemoryStoreSinkOperator.scala
	src/main/scala/shark/execution/OperatorFactory.scala
	src/main/scala/shark/execution/TableReader.scala
	src/main/scala/shark/parse/SharkSemanticAnalyzer.scala