SPARK-2277: clear host->rack info properly

Hi mridulm, I just think of this issue of [#1212](https://github.com/apache/spark/pull/1212): I added FakeRackUtil to hold the host -> rack mapping. It should be cleaned up after use so that it won't mess up with test cases others may add later.
Really sorry about this.

Author: Rui Li <rui.li@intel.com>

Closes #1454 from lirui-intel/SPARK-2277-fix-UT and squashes the following commits:

f8ea25c [Rui Li] SPARK-2277: clear host->rack info properly
SPARK-2226:  [SQL] transform HAVING clauses with aggregate expressions that aren't in the aggregation list

This change adds an analyzer rule to
  1. find expressions in `HAVING` clause filters that depend on unresolved attributes,
  2. push these expressions down to the underlying aggregates, and then
  3. project them away above the filter.

It also enables the `HAVING` queries in the Hive compatibility suite.

Author: William Benton <willb@redhat.com>

Closes #1497 from willb/spark-2226 and squashes the following commits:

92c9a93 [William Benton] Removed unnecessary import
f1d4f34 [William Benton] Cleanups missed in prior commit
0e1624f [William Benton] Incorporated suggestions from @marmbrus; thanks!
541d4ee [William Benton] Cleanups from review
5a12647 [William Benton] Explanatory comments and stylistic cleanups.
c7f2b2c [William Benton] Whitelist HAVING queries.
29a26e3 [William Benton] Added rule to handle unresolved attributes in HAVING clauses (SPARK-2226)
[SPARK-2569][SQL] Fix shipping of TEMPORARY hive UDFs.

Instead of shipping just the name and then looking up the info on the workers, we now ship the whole classname.  Also, I refactored the file as it was getting pretty large to move out the type conversion code to its own file.

Author: Michael Armbrust <michael@databricks.com>

Closes #1552 from marmbrus/fixTempUdfs and squashes the following commits:

b695904 [Michael Armbrust] Make add jar execute with Hive.  Ship the whole function class name since sometimes we cannot lookup temporary functions on the workers.
[SPARK-2102][SQL][CORE] Add option for kryo registration required and use a resource pool in Spark SQL for Kryo instances.

Author: Ian O Connell <ioconnell@twitter.com>

Closes #1377 from ianoc/feature/SPARK-2102 and squashes the following commits:

5498566 [Ian O Connell] Docs update suggested by Patrick
20e8555 [Ian O Connell] Slight style change
f92c294 [Ian O Connell] Add docs for new KryoSerializer option
f3735c8 [Ian O Connell] Add using a kryo resource pool for the SqlSerializer
4e5c342 [Ian O Connell] Register the SparkConf for kryo, it gets swept into serialization
665805a [Ian O Connell] Add a spark.kryo.registrationRequired option for configuring the Kryo Serializer