[SPARK-4191][SQL]move wrapperFor to HiveInspectors to reuse it

Move wrapperFor in InsertIntoHiveTable to HiveInspectors to reuse them, this method can be reused when writing date with ObjectInspector(such as orc support)

Author: wangfei <wangfei1@huawei.com>
Author: scwf <wangfei1@huawei.com>

Closes #3057 from scwf/reuse-wraperfor and squashes the following commits:

7ccf932 [scwf] fix conflicts
d44f4da [wangfei] fix imports
9bf1b50 [wangfei] revert no related change
9a5276a [wangfei] move wrapfor to hiveinspector to reuse them
[SPARK-4185][SQL] JSON schema inference failed when dealing with type conflicts in arrays

JIRA: https://issues.apache.org/jira/browse/SPARK-4185.

This PR also has the fix of #3052.

Author: Yin Huai <huai@cse.ohio-state.edu>

Closes #3056 from yhuai/SPARK-4185 and squashes the following commits:

ed3a5a8 [Yin Huai] Correctly handle type conflicts between structs and primitive types in an array.
[SPARK-2189][SQL] Adds dropTempTable API

This PR adds an API for unregistering temporary tables. If a temporary table has been cached before, it's unpersisted as well.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #3039 from liancheng/unregister-temp-table and squashes the following commits:

54ae99f [Cheng Lian] Fixes Scala styling issue
1948c14 [Cheng Lian] Removes the unpersist argument
aca41d3 [Cheng Lian] Ensures thread safety
7d4fb2b [Cheng Lian] Adds unregisterTempTable API
[SPARK-4183] Close transport-related resources between SparkContexts

A leak of event loops may be causing test failures.

Author: Aaron Davidson <aaron@databricks.com>

Closes #3053 from aarondav/leak and squashes the following commits:

e676d18 [Aaron Davidson] Typo!
8f96475 [Aaron Davidson] Keep original ssc semantics
7e49f10 [Aaron Davidson] A leak of event loops may be causing test failures.