[SPARK-4756][SQL] FIX: sessionToActivePool grow infinitely, even as sessions expire

**sessionToActivePool** in **SparkSQLOperationManager** grow infinitely, even as sessions expire.
we should remove the pool value when the session closed, even though **sessionToActivePool** would not exist in all of sessions.

Author: guowei2 <guowei2@asiainfo.com>

Closes #3617 from guowei2/SPARK-4756 and squashes the following commits:

e9b97b8 [guowei2] fix compile bug with Shim12
cf0f521 [guowei2] Merge remote-tracking branch 'apache/master' into SPARK-4756
e070998 [guowei2] fix: remove active pool of the session when it expired
[SPARK-4693] [SQL] PruningPredicates may be wrong if predicates contains an empty AttributeSet() references

The sql "select * from spark_test::for_test where abs(20141202) is not null" has predicates=List(IS NOT NULL HiveSimpleUdf#org.apache.hadoop.hive.ql.udf.UDFAbs(20141202)) and
partitionKeyIds=AttributeSet(). PruningPredicates is List(IS NOT NULL HiveSimpleUdf#org.apache.hadoop.hive.ql.udf.UDFAbs(20141202)). Then the exception "java.lang.IllegalArgumentException: requirement failed: Partition pruning predicates only supported for partitioned tables." is thrown.
The sql "select * from spark_test::for_test_partitioned_table where abs(20141202) is not null and type_id=11 and platform = 3" with partitioned key insert_date has predicates=List(IS NOT NULL HiveSimpleUdf#org.apache.hadoop.hive.ql.udf.UDFAbs(20141202), (type_id#12 = 11), (platform#8 = 3)) and partitionKeyIds=AttributeSet(insert_date#24). PruningPredicates is List(IS NOT NULL HiveSimpleUdf#org.apache.hadoop.hive.ql.udf.UDFAbs(20141202)).

Author: YanTangZhai <hakeemzhai@tencent.com>
Author: yantangzhai <tyz0303@163.com>

Closes #3556 from YanTangZhai/SPARK-4693 and squashes the following commits:

620ebe3 [yantangzhai] [SPARK-4693] [SQL] PruningPredicates may be wrong if predicates contains an empty AttributeSet() references
37cfdf5 [yantangzhai] [SPARK-4693] [SQL] PruningPredicates may be wrong if predicates contains an empty AttributeSet() references
70a3544 [yantangzhai] [SPARK-4693] [SQL] PruningPredicates may be wrong if predicates contains an empty AttributeSet() references
efa9b03 [YanTangZhai] Update HiveQuerySuite.scala
72accf1 [YanTangZhai] Update HiveQuerySuite.scala
e572b9a [YanTangZhai] Update HiveStrategies.scala
6e643f8 [YanTangZhai] Merge pull request #11 from apache/master
e249846 [YanTangZhai] Merge pull request #10 from apache/master
d26d982 [YanTangZhai] Merge pull request #9 from apache/master
76d4027 [YanTangZhai] Merge pull request #8 from apache/master
03b62b0 [YanTangZhai] Merge pull request #7 from apache/master
8a00106 [YanTangZhai] Merge pull request #6 from apache/master
cbcba66 [YanTangZhai] Merge pull request #3 from apache/master
cdef539 [YanTangZhai] Merge pull request #1 from apache/master
[SPARK-2554][SQL] Supporting SumDistinct partial aggregation

Adding support to the partial aggregation of SumDistinct

Author: ravipesala <ravindra.pesala@huawei.com>

Closes #3348 from ravipesala/SPARK-2554 and squashes the following commits:

fd28e4d [ravipesala] Fixed review comments
e60e67f [ravipesala] Fixed test cases and made it as nullable
32fe234 [ravipesala] Supporting SumDistinct partial aggregation Conflicts: 	sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
[SPARK-4573] [SQL] Add SettableStructObjectInspector support in "wrap" function

Hive UDAF may create an customized object constructed by SettableStructObjectInspector, this is critical when integrate Hive UDAF with the refactor-ed UDAF interface.

Performance issue in `wrap/unwrap` since more match cases added, will do it in another PR.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #3429 from chenghao-intel/settable_oi and squashes the following commits:

9f0aff3 [Cheng Hao] update code style issues as feedbacks
2b0561d [Cheng Hao] Add more scala doc
f5a40e8 [Cheng Hao] add scala doc
2977e9b [Cheng Hao] remove the timezone setting for test suite
3ed284c [Cheng Hao] fix the date type comparison
f1b6749 [Cheng Hao] Update the comment
932940d [Cheng Hao] Add more unit test
72e4332 [Cheng Hao] Add settable StructObjectInspector support
[SPARK-4861][SQL] Refactory command in spark sql

Remove ```Command``` and use ```RunnableCommand``` instead.

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

Closes #3712 from scwf/cmd and squashes the following commits:

51a82f2 [wangfei] fix test failure
0e03be8 [wangfei] address comments
4033bed [scwf] remove CreateTableAsSelect in hivestrategy
5d20010 [wangfei] address comments
125f542 [scwf] factory command in spark sql
[SPARK-4728][MLLib] Add exponential, gamma, and log normal sampling to MLlib da...

...ta generators

This patch adds:

* Exponential, gamma, and log normal generators that wrap Apache Commons math3 to the private API
* Functions for generating exponential, gamma, and log normal RDDs and vector RDDs
* Tests for the above

Author: RJ Nowling <rnowling@gmail.com>

Closes #3680 from rnowling/spark4728 and squashes the following commits:

455f50a [RJ Nowling] Add tests for exponential, gamma, and log normal samplers to JavaRandomRDDsSuite
3e1134a [RJ Nowling] Fix val/var, unncessary creation of Distribution objects when setting seeds, and import line longer than line wrap limits
58f5b97 [RJ Nowling] Fix bounds in tests so they scale with variance, not stdev
84fd98d [RJ Nowling] Add more values for testing distributions.
9f96232 [RJ Nowling] [SPARK-4728] Add exponential, gamma, and log normal sampling to MLlib data generators