[SPARK-4685] Include all spark.ml and spark.mllib packages in JavaDoc's MLlib group

This is #3554 from Lewuathe except that I put both `spark.ml` and `spark.mllib` in the group 'MLlib`.

Closes #3554

jkbradley

Author: lewuathe <lewuathe@me.com>
Author: Xiangrui Meng <meng@databricks.com>

Closes #3598 from mengxr/Lewuathe-modify-javadoc-setting and squashes the following commits:

184609a [Xiangrui Meng] merge spark.ml and spark.mllib into the same group in javadoc
f7535e6 [lewuathe] [SPARK-4685] Update JavaDoc settings to include spark.ml and all spark.mllib subpackages in the right sections

(cherry picked from commit 20bfea4ab7c0923e8d3f039d0c5098669db4d5b0)
Signed-off-by: Xiangrui Meng <meng@databricks.com>
[SQL] Minor: Avoid calling Seq#size in a loop

Just found this instance while doing some jstack-based profiling of a Spark SQL job. It is very unlikely that this is causing much of a perf issue anywhere, but it is unnecessarily suboptimal.

Author: Aaron Davidson <aaron@databricks.com>

Closes #3593 from aarondav/seq-opt and squashes the following commits:

962cdfc [Aaron Davidson] [SQL] Minor: Avoid calling Seq#size in a loop

(cherry picked from commit c6c7165e7ecf1690027d6bd4e0620012cd0d2310)
Signed-off-by: Reynold Xin <rxin@databricks.com>
[docs] Fix outdated comment in tuning guide

When you use the SPARK_JAVA_OPTS env variable, Spark complains:

```
SPARK_JAVA_OPTS was detected (set to ' -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps ').
This is deprecated in Spark 1.0+.

Please instead use:
 - ./spark-submit with conf/spark-defaults.conf to set defaults for an application
 - ./spark-submit with --driver-java-options to set -X options for a driver
 - spark.executor.extraJavaOptions to set -X options for executors
 - SPARK_DAEMON_JAVA_OPTS to set java options for standalone daemons (master or worker)
```

This updates the docs to redirect the user to the relevant part of the configuration docs.

CC: mengxr  but please CC someone else as needed

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #3592 from jkbradley/tuning-doc and squashes the following commits:

0760ce1 [Joseph K. Bradley] fixed outdated comment in tuning guide

(cherry picked from commit 529439bd506949f272a2b6f099ea549b097428f3)
Signed-off-by: Reynold Xin <rxin@databricks.com>
[SPARK-4575] [mllib] [docs] spark.ml pipelines doc + bug fixes

Documentation:
* Added ml-guide.md, linked from mllib-guide.md
* Updated mllib-guide.md with small section pointing to ml-guide.md

Examples:
* CrossValidatorExample
* SimpleParamsExample
* (I copied these + the SimpleTextClassificationPipeline example into the ml-guide.md)

Bug fixes:
* PipelineModel: did not use ParamMaps correctly
* UnaryTransformer: issues with TypeTag serialization (Thanks to mengxr for that fix!)

CC: mengxr shivaram  etrain  Documentation for Pipelines: I know the docs are not complete, but the goal is to have enough to let interested people get started using spark.ml and to add more docs once the package is more established/complete.

Author: Joseph K. Bradley <joseph@databricks.com>
Author: jkbradley <joseph.kurata.bradley@gmail.com>
Author: Xiangrui Meng <meng@databricks.com>

Closes #3588 from jkbradley/ml-package-docs and squashes the following commits:

d393b5c [Joseph K. Bradley] fixed bug in Pipeline (typo from last commit).  updated examples for CV and Params for spark.ml
c38469c [Joseph K. Bradley] Updated ml-guide with CV examples
99f88c2 [Joseph K. Bradley] Fixed bug in PipelineModel.transform* with usage of params.  Updated CrossValidatorExample to use more training examples so it is less likely to get a 0-size fold.
ea34dc6 [jkbradley] Merge pull request #4 from mengxr/ml-package-docs
3b83ec0 [Xiangrui Meng] replace TypeTag with explicit datatype
41ad9b1 [Joseph K. Bradley] Added examples for spark.ml: SimpleParamsExample + Java version, CrossValidatorExample + Java version.  CrossValidatorExample not working yet.  Added programming guide for spark.ml, but need to add CrossValidatorExample to it once CrossValidatorExample works.

(cherry picked from commit 469a6e5f3bdd5593b3254bc916be8236e7c6cb74)
Signed-off-by: Xiangrui Meng <meng@databricks.com>