SPARK-2869 - Fix tiny bug in JdbcRdd for closing jdbc connection

I inquired on  dev mailing list about the motivation for checking the jdbc statement instead of the connection in the close() logic of JdbcRDD. Ted Yu believes there essentially is none-  it is a simple cut and paste issue. So here is the tiny fix to patch it.

Author: Stephen Boesch <javadba>
Author: Stephen Boesch <javadba@gmail.com>

Closes #1792 from javadba/closejdbc and squashes the following commits:

363be4f [Stephen Boesch] SPARK-2869 - Fix tiny bug in JdbcRdd for closing jdbc connection (reformat with braces)
6518d36 [Stephen Boesch] SPARK-2689 Fix tiny bug in JdbcRdd for closing jdbc connection
3fb23ed [Stephen Boesch] SPARK-2689 Fix potential leak of connection/PreparedStatement in case of error in JdbcRDD
095b2c9 [Stephen Boesch] Fix tiny bug (likely copy and paste error) in closing jdbc connection
[sql] rename project name in pom.xml of hive-thriftserver module

module spark-hive-thriftserver_2.10 and spark-hive_2.10 both named "Spark Project Hive" in pom.xml, so rename spark-hive-thriftserver_2.10 project name to "Spark Project Hive Thrift Server"

Author: wangfei <wangfei1@huawei.com>

Closes #1789 from scwf/patch-1 and squashes the following commits:

ca1f5e9 [wangfei] [sql] rename module name of hive-thriftserver
[SPARK-2650][SQL] Try to partially fix SPARK-2650 by adjusting initial buffer size and reducing memory allocation

JIRA issue: [SPARK-2650](https://issues.apache.org/jira/browse/SPARK-2650)

Please refer to [comments](https://issues.apache.org/jira/browse/SPARK-2650?focusedCommentId=14084397&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14084397) of SPARK-2650 for some other details.

This PR adjusts the initial in-memory columnar buffer size to 1MB, same as the default value of Shark's `shark.column.partitionSize.mb` property when running in local mode. Will add Shark style partition size estimation in another PR.

Also, before this PR, `NullableColumnBuilder` copies the whole buffer to add the null positions section, and then `CompressibleColumnBuilder` copies and compresses the buffer again, even if compression is disabled (`PassThrough` compression scheme is used to disable compression). In this PR the first buffer copy is eliminated to reduce memory consumption.

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

Closes #1769 from liancheng/spark-2650 and squashes the following commits:

88a042e [Cheng Lian] Fixed method visibility and removed dead code
001f2e5 [Cheng Lian] Try fixing SPARK-2650 by adjusting initial buffer size and reducing memory allocation
[SPARK-2854][SQL] Finalize _acceptable_types in pyspark.sql

This PR aims to finalize accepted data value types in Python RDDs provided to Python `applySchema`.

JIRA: https://issues.apache.org/jira/browse/SPARK-2854

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

Closes #1793 from yhuai/SPARK-2854 and squashes the following commits:

32f0708 [Yin Huai] LongType only accepts long values.
c2b23dd [Yin Huai] Do data type conversions based on the specified Spark SQL data type.