Fix: sbt test throw an java.lang.OutOfMemoryError: PermGen space

Author: witgo <witgo@qq.com>

Closes #773 from witgo/sbt_javaOptions and squashes the following commits:

26c7d38 [witgo] Improve sbt configuration
SPARK-1829 Sub-second durations shouldn't round to "0 s"

As "99 ms" up to 99 ms
As "0.1 s" from 0.1 s up to 0.9 s

https://issues.apache.org/jira/browse/SPARK-1829

Compare the first image to the second here: http://imgur.com/RaLEsSZ,7VTlgfo#0

Author: Andrew Ash <andrew@andrewash.com>

Closes #768 from ash211/spark-1829 and squashes the following commits:

1c15b8e [Andrew Ash] SPARK-1829 Format sub-second durations more appropriately
SPARK-1833 - Have an empty SparkContext constructor.

This is nicer than relying on new SparkContext(new SparkConf())

Author: Patrick Wendell <pwendell@gmail.com>

Closes #774 from pwendell/spark-context and squashes the following commits:

ef9f12f [Patrick Wendell] SPARK-1833 - Have an empty SparkContext constructor.
[FIX] do not load defaults when testing SparkConf in pyspark

The default constructor loads default properties, which can fail the test.

Author: Xiangrui Meng <meng@databricks.com>

Closes #775 from mengxr/pyspark-conf-fix and squashes the following commits:

83ef6c4 [Xiangrui Meng] do not load defaults when testing SparkConf in pyspark
String interpolation + some other small changes

After having been invited to make the change in https://github.com/apache/spark/commit/6bee01dd04ef73c6b829110ebcdd622d521ea8ff#commitcomment-6284165 by @witgo.

Author: Jacek Laskowski <jacek@japila.pl>

Closes #748 from jaceklaskowski/sparkenv-string-interpolation and squashes the following commits:

be6ebac [Jacek Laskowski] String interpolation + some other small changes
[SPARK-1696][MLLIB] use alpha in dense dspr

It doesn't affect existing code because only `alpha = 1.0` is used in the code.

Author: Xiangrui Meng <meng@databricks.com>

Closes #778 from mengxr/mllib-dspr-fix and squashes the following commits:

a37402e [Xiangrui Meng] use alpha in dense dspr
[Typo] propertes -> properties

Author: andrewor14 <andrewor14@gmail.com>

Closes #780 from andrewor14/submit-typo and squashes the following commits:

e70e057 [andrewor14] propertes -> properties
[SPARK-1826] fix the head notation of package object dsl

Author: wangfei <scnbwf@yeah.net>

Closes #765 from scwf/dslfix and squashes the following commits:

d2d1a9d [wangfei] Update package.scala
66ff53b [wangfei] fix the head notation of package object dsl
default task number misleading in several places

  private[streaming] def defaultPartitioner(numPartitions: Int = self.ssc.sc.defaultParallelism){
    new HashPartitioner(numPartitions)
  }

it represents that the default task number in Spark Streaming relies on the variable defaultParallelism in SparkContext, which is decided by the config property spark.default.parallelism

the property "spark.default.parallelism" refers to https://github.com/apache/spark/pull/389

Author: Chen Chao <crazyjvm@gmail.com>

Closes #766 from CrazyJvm/patch-7 and squashes the following commits:

0b7efba [Chen Chao] Update streaming-programming-guide.md
cc5b66c [Chen Chao] default task number misleading in several places
[SPARK-1840] SparkListenerBus prints out scary error message when terminated normally

Running SparkPi example gave this error.
```
Pi is roughly 3.14374
14/05/14 18:16:19 ERROR Utils: Uncaught exception in thread SparkListenerBus
scala.runtime.NonLocalReturnControl$mcV$sp
```
This is due to the catch-all in the SparkListenerBus, which logged control throwable used by scala system

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #783 from tdas/controlexception-fix and squashes the following commits:

a466c8d [Tathagata Das] Ignored control exceptions when logging all exceptions.
Add language tabs and Python version to interactive part of quick-start

This is an addition of some stuff that was missed in https://issues.apache.org/jira/browse/SPARK-1567. I've also updated the doc to show submitting the Python application with spark-submit.

Author: Matei Zaharia <matei@databricks.com>

Closes #782 from mateiz/spark-1567-extra and squashes the following commits:

6f8f2aa [Matei Zaharia] tweaks
9ed9874 [Matei Zaharia] tweaks
ae67c3e [Matei Zaharia] tweak
b303ba3 [Matei Zaharia] tweak
1433a4d [Matei Zaharia] Add language tabs and Python version to interactive part of quick-start guide
Documentation: Encourage use of reduceByKey instead of groupByKey.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #784 from pwendell/group-by-key and squashes the following commits:

9b4505f [Patrick Wendell] Small fix
6347924 [Patrick Wendell] Documentation: Encourage use of reduceByKey instead of groupByKey.
Package docs

This is a few changes based on the original patch by @scrapcodes.

Author: Prashant Sharma <prashant.s@imaginea.com>
Author: Patrick Wendell <pwendell@gmail.com>

Closes #785 from pwendell/package-docs and squashes the following commits:

c32b731 [Patrick Wendell] Changes based on Prashant's patch
c0463d3 [Prashant Sharma] added eof new line
ce8bf73 [Prashant Sharma] Added eof new line to all files.
4c35f2e [Prashant Sharma] SPARK-1563 Add package-info.java and package.scala files for all packages that appear in docs
fix different versions of commons-lang dependency and apache/spark#746 addendum

Author: witgo <witgo@qq.com>

Closes #754 from witgo/commons-lang and squashes the following commits:

3ebab31 [witgo] merge master
f3b8fa2 [witgo] merge master
2083fae [witgo] repeat definition
5599cdb [witgo] multiple version of sbt  dependency
c1b66a1 [witgo] fix different versions of commons-lang dependency
Merge branch 'master' of github.com:apache/spark into pyspark-submit