[SPARK-2431][SQL] Refine StringComparison and related codes.

Refine `StringComparison` and related codes as follows:
- `StringComparison` could be similar to `StringRegexExpression` or `CaseConversionExpression`.
- Nullability of `StringRegexExpression` could depend on children's nullabilities.
- Add a case that the like condition includes no wildcard to `LikeSimplification`.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #1357 from ueshin/issues/SPARK-2431 and squashes the following commits:

77766f5 [Takuya UESHIN] Add a case that the like condition includes no wildcard to LikeSimplification.
b9da9d2 [Takuya UESHIN] Fix nullability of StringRegexExpression.
680bb72 [Takuya UESHIN] Refine StringComparison.
[SPARK-2415] [SQL] RowWriteSupport should handle empty ArrayType correctly.

`RowWriteSupport` doesn't write empty `ArrayType` value, so the read value becomes `null`.
It should write empty `ArrayType` value as it is.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #1339 from ueshin/issues/SPARK-2415 and squashes the following commits:

32afc87 [Takuya UESHIN] Merge branch 'master' into issues/SPARK-2415
2f05196 [Takuya UESHIN] Fix RowWriteSupport to handle empty ArrayType correctly.
[SPARK-2428][SQL] Add except and intersect methods to SchemaRDD.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #1355 from ueshin/issues/SPARK-2428 and squashes the following commits:

b6fa264 [Takuya UESHIN] Add except and intersect methods to SchemaRDD.
[SPARK-2358][MLLIB] Add an option to include native BLAS/LAPACK loader in the build

It would be easy for users to include the netlib-java jniloader in the spark jar, which is LGPL-licensed. We can follow the same approach as ganglia support in Spark, which could be enabled by turning on "-Pganglia-lgpl" at build time. We can use "-Pnetlib-lgpl" flag for this.

Author: Xiangrui Meng <meng@databricks.com>

Closes #1295 from mengxr/netlib-lgpl and squashes the following commits:

aebf001 [Xiangrui Meng] add a profile to optionally include native BLAS/LAPACK loader in mllib
fix Graph partitionStrategy comment

Author: CrazyJvm <crazyjvm@gmail.com>

Closes #1368 from CrazyJvm/graph-comment-1 and squashes the following commits:

d47f3c5 [CrazyJvm] fix style
e190d6f [CrazyJvm] fix Graph partitionStrategy comment
[Minor] Remove unused val in Master

Author: Andrew Or <andrewor14@gmail.com>

Closes #1365 from andrewor14/master-fs and squashes the following commits:

497f100 [Andrew Or] Sneak in a space and hope no one will notice
05ba6da [Andrew Or] Remove unused val
[SPARK-2437] Rename MAVEN_PROFILES to SBT_MAVEN_PROFILES and add SBT_MAVEN_PROPERTIES

NOTE: It is not possible to use both env variable  `SBT_MAVEN_PROFILES`  and `-P` flag at same time. `-P` if specified takes precedence.

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #1374 from ScrapCodes/SPARK-2437/rename-MAVEN_PROFILES and squashes the following commits:

8694bde [Prashant Sharma] [SPARK-2437] Rename MAVEN_PROFILES to SBT_MAVEN_PROFILES and add SBT_MAVEN_PROPERTIES
[SPARK-2457] Inconsistent description in README about build option

Now, we should use -Pyarn instead of SPARK_YARN when building but README says as follows.

    For Apache Hadoop 2.2.X, 2.1.X, 2.0.X, 0.23.x, Cloudera CDH MRv2, and other Hadoop versions
    with YARN, also set `SPARK_YARN=true`:

      # Apache Hadoop 2.0.5-alpha
      $ sbt/sbt -Dhadoop.version=2.0.5-alpha -Pyarn assembly

      # Cloudera CDH 4.2.0 with MapReduce v2
      $ sbt/sbt -Dhadoop.version=2.0.0-cdh4.2.0 -Pyarn assembly

      # Apache Hadoop 2.2.X and newer
      $ sbt/sbt -Dhadoop.version=2.2.0 -Pyarn assembly

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #1382 from sarutak/SPARK-2457 and squashes the following commits:

e7b2d64 [Kousuke Saruta] Replaced "SPARK_YARN=true" with "-Pyarn" in README
[SPARK-1969][MLlib] Online summarizer APIs for mean, variance, min, and max

It basically moved the private ColumnStatisticsAggregator class from RowMatrix to public available DeveloperApi with documentation and unitests.

Changes:
1) Moved the private implementation from org.apache.spark.mllib.linalg.ColumnStatisticsAggregator to org.apache.spark.mllib.stat.MultivariateOnlineSummarizer
2) When creating OnlineSummarizer object, the number of columns is not needed in the constructor. It's determined when users add the first sample.
3) Added the APIs documentation for MultivariateOnlineSummarizer.
4) Added the unittests for MultivariateOnlineSummarizer.

Author: DB Tsai <dbtsai@dbtsai.com>

Closes #955 from dbtsai/dbtsai-summarizer and squashes the following commits:

b13ac90 [DB Tsai] dbtsai-summarizer
use specialized axpy in RowMatrix for SVD

After running some more tests on large matrix, found that the BV axpy (breeze/linalg/Vector.scala, axpy) is slower than the BSV axpy (breeze/linalg/operators/SparseVectorOps.scala, sv_dv_axpy), 8s v.s. 2s for each multiplication. The BV axpy operates on an iterator while BSV axpy directly operates on the underlying array. I think the overhead comes from creating the iterator (with a zip) and advancing the pointers.

Author: Li Pu <lpu@twitter.com>
Author: Xiangrui Meng <meng@databricks.com>
Author: Li Pu <li.pu@outlook.com>

Closes #1378 from vrilleup/master and squashes the following commits:

6fb01a3 [Li Pu] use specialized axpy in RowMatrix
5255f2a [Li Pu] Merge remote-tracking branch 'upstream/master'
7312ec1 [Li Pu] very minor comment fix
4c618e9 [Li Pu] Merge pull request #1 from mengxr/vrilleup-master
a461082 [Xiangrui Meng] make superscript show up correctly in doc
861ec48 [Xiangrui Meng] simplify axpy
62969fa [Xiangrui Meng] use BDV directly in symmetricEigs change the computation mode to local-svd, local-eigs, and dist-eigs update tests and docs
c273771 [Li Pu] automatically determine SVD compute mode and parameters
7148426 [Li Pu] improve RowMatrix multiply
5543cce [Li Pu] improve svd api
819824b [Li Pu] add flag for dense svd or sparse svd
eb15100 [Li Pu] fix binary compatibility
4c7aec3 [Li Pu] improve comments
e7850ed [Li Pu] use aggregate and axpy
827411b [Li Pu] fix EOF new line
9c80515 [Li Pu] use non-sparse implementation when k = n
fe983b0 [Li Pu] improve scala style
96d2ecb [Li Pu] improve eigenvalue sorting
e1db950 [Li Pu] SPARK-1782: svd for sparse matrix using ARPACK
Use the Executor's ClassLoader in sc.objectFile().

This makes it possible to read classes from the object file which were specified in the user-provided jars. (By default ObjectInputStream uses latestUserDefinedLoader, which may or may not be the right one.)

I created this because I ran into the following problem. I have x:RDD[X] with X being defined in the jar that I provide to SparkContext. I save it with x.saveAsObjectFile("x"). I try to load it with sc.objectFile\[X\]("x"). It fails with ClassNotFoundException.

After a good while of debugging I figured out that Utils.deserialize() most likely uses the ClassLoader of Utils. This is the bootstrap ClassLoader, so it is not aware of the dynamically added jars. This patch fixes the issue.

A more robust fix would be to always default to Thread.currentThread.getContextClassLoader. This would prevent this problem from biting anyone in the future. It would be a bit harder to test though. On the topic of testing, if you'd like to see tests for this, I will need some hand-holding. Thanks!

Author: Daniel Darabos <darabos.daniel@gmail.com>

Closes #181 from darabos/master and squashes the following commits:

45a011a [Daniel Darabos] Add test for SPARK-1877. (Fixed in 52eb54d.)
e13e090 [Daniel Darabos] Merge branch 'master' of https://github.com/apache/spark
61fe0d0 [Daniel Darabos] Fix style (line too long).
1b5df2c [Daniel Darabos] Use the Executor's ClassLoader in sc.objectFile(). This makes it possible to read classes from the object file which were specified in the user-provided jars. (By default ObjectInputStream uses latestUserDefinedLoader, which may or may not be the right one.)
[SPARK-2455] Mark (Shippable)VertexPartition serializable

VertexPartition and ShippableVertexPartition are contained in RDDs but are not marked Serializable, leading to NotSerializableExceptions when using Java serialization.

The fix is simply to mark them as Serializable. This PR does that and adds a test for serializing them using Java and Kryo serialization.

Author: Ankur Dave <ankurdave@gmail.com>

Closes #1376 from ankurdave/SPARK-2455 and squashes the following commits:

ed4a51b [Ankur Dave] Make (Shippable)VertexPartition serializable
1fd42c5 [Ankur Dave] Add failing tests for Java serialization
[SPARK-2441][SQL] Add more efficient distinct operator.

Author: Michael Armbrust <michael@databricks.com>

Closes #1366 from marmbrus/partialDistinct and squashes the following commits:

12a31ab [Michael Armbrust] Add more efficient distinct operator.
[SPARK-2405][SQL] Reusue same byte buffers when creating new instance of InMemoryRelation

Reuse byte buffers when creating unique attributes for multiple instances of an InMemoryRelation in a single query plan.

Author: Michael Armbrust <michael@databricks.com>

Closes #1332 from marmbrus/doubleCache and squashes the following commits:

4a19609 [Michael Armbrust] Clean up concurrency story by calculating buffersn the constructor.
b39c931 [Michael Armbrust] Allocations are kind of a side effect.
f67eff7 [Michael Armbrust] Reusue same byte buffers when creating new instance of InMemoryRelation
SPARK-2462.  Make Vector.apply public.

Apologies if there's an already-discussed reason I missed for why this doesn't make sense.

Author: Sandy Ryza <sandy@cloudera.com>

Closes #1389 from sryza/sandy-spark-2462 and squashes the following commits:

2e5e201 [Sandy Ryza] SPARK-2462.  Make Vector.apply public.