a new PR base on new master.  changes are the same as https://github.com/apache/spark/pull/1919

Author: baishuo(白硕) <vc_java@hotmail.com>
Author: baishuo <vc_java@hotmail.com>
Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2226 from baishuo/patch-3007 and squashes the following commits:

e69ce88 [Cheng Lian] Adds tests to verify dynamic partitioning folder layout
b20a3dc [Cheng Lian] Addresses @yhuai's comments
096bbbc [baishuo(白硕)] Merge pull request #1 from liancheng/refactor-dp
1093c20 [Cheng Lian] Adds more tests
5004542 [Cheng Lian] Minor refactoring
fae9eff [Cheng Lian] Refactors InsertIntoHiveTable to a Command
528e84c [Cheng Lian] Fixes typo in test name, regenerated golden answer files
c464b26 [Cheng Lian] Refactors dynamic partitioning support
5033928 [baishuo] pass check style
2201c75 [baishuo] use HiveConf.DEFAULTPARTITIONNAME to replace hive.exec.default.partition.name
b47c9bf [baishuo] modify according micheal's advice
c3ab36d [baishuo] modify for some bad indentation
7ce2d9f [baishuo] modify code to pass scala style checks
37c1c43 [baishuo] delete a empty else branch
66e33fc [baishuo] do a little modify
88d0110 [baishuo] update file after test
a3961d9 [baishuo(白硕)] Update Cast.scala
f7467d0 [baishuo(白硕)] Update InsertIntoHiveTable.scala
c1a59dd [baishuo(白硕)] Update Cast.scala
0e18496 [baishuo(白硕)] Update HiveQuerySuite.scala
60f70aa [baishuo(白硕)] Update InsertIntoHiveTable.scala
0a50db9 [baishuo(白硕)] Update HiveCompatibilitySuite.scala
491c7d0 [baishuo(白硕)] Update InsertIntoHiveTable.scala
a2374a8 [baishuo(白硕)] Update InsertIntoHiveTable.scala
701a814 [baishuo(白硕)] Update SparkHadoopWriter.scala
dc24c41 [baishuo(白硕)] Update HiveQl.scala