[mllib] DecisionTree: treeAggregate + Python example bug fix

Small DecisionTree updates:
* Changed main DecisionTree aggregate to treeAggregate.
* Fixed bug in python example decision_tree_runner.py with missing argument (since categoricalFeaturesInfo is no longer an optional argument for trainClassifier).
* Fixed same bug in python doc tests, and added tree.py to doc tests.

CC: mengxr

Author: Joseph K. Bradley <joseph.kurata.bradley@gmail.com>

Closes #2015 from jkbradley/dt-opt2 and squashes the following commits:

b5114fa [Joseph K. Bradley] Fixed python tree.py doc test (extra newline)
8e4665d [Joseph K. Bradley] Added tree.py to python doc tests.  Fixed bug from missing categoricalFeaturesInfo argument.
b7b2922 [Joseph K. Bradley] Fixed bug in python example decision_tree_runner.py with missing argument.  Changed main DecisionTree aggregate to treeAggregate.
85bbc1f [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt2
66d076f [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt2
a0ed0da [Joseph K. Bradley] Renamed DTMetadata to DecisionTreeMetadata.  Small doc updates.
3726d20 [Joseph K. Bradley] Small code improvements based on code review.
ac0b9f8 [Joseph K. Bradley] Small updates based on code review. Main change: Now using << instead of math.pow.
db0d773 [Joseph K. Bradley] scala style fix
6a38f48 [Joseph K. Bradley] Added DTMetadata class for cleaner code
931a3a7 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt2
797f68a [Joseph K. Bradley] Fixed DecisionTreeSuite bug for training second level.  Needed to update treePointToNodeIndex with groupShift.
f40381c [Joseph K. Bradley] Merge branch 'dt-opt1' into dt-opt2
5f2dec2 [Joseph K. Bradley] Fixed scalastyle issue in TreePoint
6b5651e [Joseph K. Bradley] Updates based on code review.  1 major change: persisting to memory + disk, not just memory.
2d2aaaf [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt1
26d10dd [Joseph K. Bradley] Removed tree/model/Filter.scala since no longer used.  Removed debugging println calls in DecisionTree.scala.
356daba [Joseph K. Bradley] Merge branch 'dt-opt1' into dt-opt2
430d782 [Joseph K. Bradley] Added more debug info on binning error.  Added some docs.
d036089 [Joseph K. Bradley] Print timing info to logDebug.
e66f1b1 [Joseph K. Bradley] TreePoint * Updated doc * Made some methods private
8464a6e [Joseph K. Bradley] Moved TimeTracker to tree/impl/ in its own file, and cleaned it up.  Removed debugging println calls from DecisionTree.  Made TreePoint extend Serialiable
a87e08f [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt1
c1565a5 [Joseph K. Bradley] Small DecisionTree updates: * Simplification: Updated calculateGainForSplit to take aggregates for a single (feature, split) pair. * Internal doc: findAggForOrderedFeatureClassification
b914f3b [Joseph K. Bradley] DecisionTree optimization: eliminated filters + small changes
b2ed1f3 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt
0f676e2 [Joseph K. Bradley] Optimizations + Bug fix for DecisionTree
3211f02 [Joseph K. Bradley] Optimizing DecisionTree * Added TreePoint representation to avoid calling findBin multiple times. * (not working yet, but debugging)
f61e9d2 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
bcf874a [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
511ec85 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
a95bc22 [Joseph K. Bradley] timing for DecisionTree internals
[SPARK-2850] [SPARK-2626] [mllib] MLlib stats examples + small fixes

Added examples for statistical summarization:
* Scala: StatisticalSummary.scala
** Tests: correlation, MultivariateOnlineSummarizer
* python: statistical_summary.py
** Tests: correlation (since MultivariateOnlineSummarizer has no Python API)

Added examples for random and sampled RDDs:
* Scala: RandomAndSampledRDDs.scala
* python: random_and_sampled_rdds.py
* Both test:
** RandomRDDGenerators.normalRDD, normalVectorRDD
** RDD.sample, takeSample, sampleByKey

Added sc.stop() to all examples.

CorrelationSuite.scala
* Added 1 test for RDDs with only 1 value

RowMatrix.scala
* numCols(): Added check for numRows = 0, with error message.
* computeCovariance(): Added check for numRows <= 1, with error message.

Python SparseVector (pyspark/mllib/linalg.py)
* Added toDense() function

python/run-tests script
* Added stat.py (doc test)

CC: mengxr dorx  Main changes were examples to show usage across APIs.

Author: Joseph K. Bradley <joseph.kurata.bradley@gmail.com>

Closes #1878 from jkbradley/mllib-stats-api-check and squashes the following commits:

ea5c047 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into mllib-stats-api-check
dafebe2 [Joseph K. Bradley] Bug fixes for examples SampledRDDs.scala and sampled_rdds.py: Check for division by 0 and for missing key in maps.
8d1e555 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into mllib-stats-api-check
60c72d9 [Joseph K. Bradley] Fixed stat.py doc test to work for Python versions printing nan or NaN.
b20d90a [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into mllib-stats-api-check
4e5d15e [Joseph K. Bradley] Changed pyspark/mllib/stat.py doc tests to use NaN instead of nan.
32173b7 [Joseph K. Bradley] Stats examples update.
c8c20dc [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into mllib-stats-api-check
cf70b07 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into mllib-stats-api-check
0b7cec3 [Joseph K. Bradley] Small updates based on code review.  Renamed statistical_summary.py to correlations.py
ab48f6e [Joseph K. Bradley] RowMatrix.scala * numCols(): Added check for numRows = 0, with error message. * computeCovariance(): Added check for numRows <= 1, with error message.
65e4ebc [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into mllib-stats-api-check
8195c78 [Joseph K. Bradley] Added examples for random and sampled RDDs: * Scala: RandomAndSampledRDDs.scala * python: random_and_sampled_rdds.py * Both test: ** RandomRDDGenerators.normalRDD, normalVectorRDD ** RDD.sample, takeSample, sampleByKey
064985b [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into mllib-stats-api-check
ee918e9 [Joseph K. Bradley] Added examples for statistical summarization: * Scala: StatisticalSummary.scala ** Tests: correlation, MultivariateOnlineSummarizer * python: statistical_summary.py ** Tests: correlation (since MultivariateOnlineSummarizer has no Python API)
[SPARK-3108][MLLIB] add predictOnValues to StreamingLR and fix predictOn

It is useful in streaming to allow users to carry extra data with the prediction, for monitoring the prediction error for example. freeman-lab

Author: Xiangrui Meng <meng@databricks.com>

Closes #2023 from mengxr/predict-on-values and squashes the following commits:

cac47b8 [Xiangrui Meng] add classtag
2821b3b [Xiangrui Meng] use mapValues
0925efa [Xiangrui Meng] add predictOnValues to StreamingLR and fix predictOn
[SPARK-3114] [PySpark] Fix Python UDFs in Spark SQL.

This fixes SPARK-3114, an issue where we inadvertently broke Python UDFs in Spark SQL.

This PR modifiers the test runner script to always run the PySpark SQL tests, irrespective of whether SparkSQL itself has been modified.  It also includes Davies' fix for the bug.

Closes #2026.

Author: Josh Rosen <joshrosen@apache.org>
Author: Davies Liu <davies.liu@gmail.com>

Closes #2027 from JoshRosen/pyspark-sql-fix and squashes the following commits:

9af2708 [Davies Liu] bugfix: disable compression of command
0d8d3a4 [Josh Rosen] Always run Python Spark SQL tests.
[SPARK-3116] Remove the excessive lockings in TorrentBroadcast

Author: Reynold Xin <rxin@apache.org>

Closes #2028 from rxin/torrentBroadcast and squashes the following commits:

92c62a5 [Reynold Xin] Revert the MEMORY_AND_DISK_SER changes.
03a5221 [Reynold Xin] [SPARK-3116] Remove the excessive lockings in TorrentBroadcast
Fix typo in decision tree docs

Candidate splits were inconsistent with the example.

Author: Matt Forbes <matt@tellapart.com>

Closes #1837 from emef/tree-doc and squashes the following commits:

3be14a1 [Matt Forbes] Fix typo in decision tree docs
[SPARK-3072] YARN - Exit when reach max number failed executors

In some cases on hadoop 2.x the spark application master doesn't properly exit and hangs around for 10 minutes after its really done.  We should make sure it exits properly and stops the driver.

Author: Thomas Graves <tgraves@apache.org>

Closes #2022 from tgravescs/SPARK-3072 and squashes the following commits:

665701d [Thomas Graves] Exit when reach max number failed executors
Review feedback.
Merge branch 'master' into SPARK-2933

Conflicts:
	yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala
	yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
	yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala
	yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
Small fix to shutdown code.

Avoid an interrupted exception when shutting down from the
reporter thread. Also, make extra effort to finish the RM
connection.