SPARK-1822: Some minor cleanup work on SchemaRDD.count()

Minor cleanup following #841.

Author: Reynold Xin <rxin@apache.org>

Closes #868 from rxin/schema-count and squashes the following commits:

5442651 [Reynold Xin] SPARK-1822: Some minor cleanup work on SchemaRDD.count()

(cherry picked from commit d66642e3978a76977414c2fdaedebaad35662667)
Signed-off-by: Reynold Xin <rxin@apache.org>
Added license header for tox.ini.

(cherry picked from commit fa541f32c5b92e6868a9c99cbb2c87115d624d23)
Signed-off-by: Reynold Xin <rxin@apache.org>
[maven-release-plugin] prepare release v1.0.0-rc11
[maven-release-plugin] prepare for next development iteration
Fix PEP8 violations in examples/src/main/python.

Author: Reynold Xin <rxin@apache.org>

Closes #870 from rxin/examples-python-pep8 and squashes the following commits:

2829e84 [Reynold Xin] Fix PEP8 violations in examples/src/main/python.

(cherry picked from commit d79c2b28e17ec0b15198aaedd2e1f403d81f717e)
Signed-off-by: Reynold Xin <rxin@apache.org>
Python docstring update for sql.py.

Mostly related to the following two rules in PEP8 and PEP257:
- Line length < 72 chars.
- First line should be a concise description of the function/class.

Author: Reynold Xin <rxin@apache.org>

Closes #869 from rxin/docstring-schemardd and squashes the following commits:

7cf0cbc [Reynold Xin] Updated sql.py for pep8 docstring.
0a4aef9 [Reynold Xin] Merge branch 'master' into docstring-schemardd
6678937 [Reynold Xin] Python docstring update for sql.py.

(cherry picked from commit 14f0358b2a0a9b92526bdad6d501ab753459eaa0)
Signed-off-by: Reynold Xin <rxin@apache.org>
Fix PEP8 violations in Python mllib.

Author: Reynold Xin <rxin@apache.org>

Closes #871 from rxin/mllib-pep8 and squashes the following commits:

848416f [Reynold Xin] Fixed a typo in the previous cleanup (c -> sc).
a8db4cd [Reynold Xin] Fix PEP8 violations in Python mllib.

(cherry picked from commit d33d3c61ae9e4551aed0217e525a109e678298f2)
Signed-off-by: Reynold Xin <rxin@apache.org>
SPARK-1903 Document Spark's network connections

https://issues.apache.org/jira/browse/SPARK-1903

Author: Andrew Ash <andrew@andrewash.com>

Closes #856 from ash211/SPARK-1903 and squashes the following commits:

6e7782a [Andrew Ash] Add the technology used on each port
1d9b5d3 [Andrew Ash] Document port for history server
56193ee [Andrew Ash] spark.ui.port becomes worker.ui.port and master.ui.port
a774c07 [Andrew Ash] Wording in network section
90e8237 [Andrew Ash] Use real :toc instead of the hand-written one
edaa337 [Andrew Ash] Master -> Standalone Cluster Master
57e8869 [Andrew Ash] Port -> Default Port
3d4d289 [Andrew Ash] Title to title case
c7d42d9 [Andrew Ash] [WIP] SPARK-1903 Add initial port listing for documentation
a416ae9 [Andrew Ash] Word wrap to 100 lines

(cherry picked from commit 0659529614c804e0c04efc59cb67dab3a6cdc9d9)
Signed-off-by: Reynold Xin <rxin@apache.org>
[SQL] Minor: Introduce SchemaRDD#aggregate() for simple aggregations

```scala
rdd.aggregate(Sum('val))
```
is just shorthand for

```scala
rdd.groupBy()(Sum('val))
```

but seems be more natural than doing a groupBy with no grouping expressions when you really just want an aggregation over all rows.

Did not add a JavaSchemaRDD or Python API, as these seem to be lacking several other methods like groupBy() already -- leaving that cleanup for future patches.

Author: Aaron Davidson <aaron@databricks.com>

Closes #874 from aarondav/schemardd and squashes the following commits:

e9e68ee [Aaron Davidson] Add comment
db6afe2 [Aaron Davidson] Introduce SchemaRDD#aggregate() for simple aggregations

(cherry picked from commit c3576ffcd7910e38928f233a824dd9e037cde05f)
Signed-off-by: Reynold Xin <rxin@apache.org>
HOTFIX: Add no-arg SparkContext constructor in Java

Self explanatory.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #878 from pwendell/java-constructor and squashes the following commits:

2cc1605 [Patrick Wendell] HOTFIX: Add no-arg SparkContext constructor in Java

(cherry picked from commit b6d22af040073cd611b0fcfdf8a5259c0dfd854c)
Signed-off-by: Aaron Davidson <aaron@databricks.com>
Revert "[maven-release-plugin] prepare for next development iteration"

This reverts commit 832dc594e7666f1d402334f8015ce29917d9c888.
Revert "[maven-release-plugin] prepare release v1.0.0-rc11"

This reverts commit 2f1dc868e5714882cf40d2633fb66772baf34789.
Updated CHANGES.txt
[maven-release-plugin] prepare release v1.0.0-rc11
[maven-release-plugin] prepare for next development iteration
[SPARK-1914] [SQL] Simplify CountFunction not to traverse to evaluate all child expressions.

`CountFunction` should count up only if the child's evaluated value is not null.

Because it traverses to evaluate all child expressions, even if the child is null, it counts up if one of the all children is not null.

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

Closes #861 from ueshin/issues/SPARK-1914 and squashes the following commits:

3b37315 [Takuya UESHIN] Merge branch 'master' into issues/SPARK-1914
2afa238 [Takuya UESHIN] Simplify CountFunction not to traverse to evaluate all child expressions.

(cherry picked from commit d6395d86f90d1c47c5b6ad17c618b56e00b7fc85)
Signed-off-by: Reynold Xin <rxin@apache.org>