[SPARK-1371] fix computePreferredLocations signature to not depend on underlying implementation

Change to Map and Set - not mutable HashMap and HashSet

Author: Mridul Muralidharan <mridulm80@apache.org>

Closes #302 from mridulm/master and squashes the following commits:

df747af [Mridul Muralidharan] Address review comments
17e2907 [Mridul Muralidharan] fix computePreferredLocations signature to not depend on underlying implementation
Fix for PR #195 for Java 6

Use Java 6's recommended equivalent of Java 7's Logger.getGlobal() to retain Java 6 compatibility. See PR #195

Author: Sean Owen <sowen@cloudera.com>

Closes #334 from srowen/FixPR195ForJava6 and squashes the following commits:

f92fbd3 [Sean Owen] Use Java 6's recommended equivalent of Java 7's Logger.getGlobal() to retain Java 6 compatibility
SPARK-1421. Make MLlib work on Python 2.6

The reason it wasn't working was passing a bytearray to stream.write(), which is not supported in Python 2.6 but is in 2.7. (This array came from NumPy when we converted data to send it over to Java). Now we just convert those bytearrays to strings of bytes, which preserves nonprintable characters as well.

Author: Matei Zaharia <matei@databricks.com>

Closes #335 from mateiz/mllib-python-2.6 and squashes the following commits:

f26c59f [Matei Zaharia] Update docs to no longer say we need Python 2.7
a84d6af [Matei Zaharia] SPARK-1421. Make MLlib work on Python 2.6
Fix SPARK-1420 The maven build error for Spark Catalyst

Author: witgo <witgo@qq.com>

Closes #333 from witgo/SPARK-1420 and squashes the following commits:

902519e [witgo] add dependency scala-reflect to catalyst
[SPARK-1259] Make RDD locally iterable

Author: Egor Pakhomov <pahomov.egor@gmail.com>

Closes #156 from epahomov/SPARK-1259 and squashes the following commits:

8ec8f24 [Egor Pakhomov] Make to local iterator shorter
34aa300 [Egor Pakhomov] Fix toLocalIterator docs
08363ef [Egor Pakhomov] SPARK-1259 from toLocallyIterable to toLocalIterator
6a994eb [Egor Pakhomov] SPARK-1259 Make RDD locally iterable
8be3dcf [Egor Pakhomov] SPARK-1259 Make RDD locally iterable
33ecb17 [Egor Pakhomov] SPARK-1259 Make RDD locally iterable
SPARK-1387. Update build plugins, avoid plugin version warning, centralize versions

Another handful of small build changes to organize and standardize a bit, and avoid warnings:

- Update Maven plugin versions for good measure
- Since plugins need maven 3.0.4 already, require it explicitly (<3.0.4 had some bugs anyway)
- Use variables to define versions across dependencies where they should move in lock step
- ... and make this consistent between Maven/SBT

OK, I also updated the JIRA URL while I was at it here.

Author: Sean Owen <sowen@cloudera.com>

Closes #291 from srowen/SPARK-1387 and squashes the following commits:

461eca1 [Sean Owen] Couldn't resist also updating JIRA location to new one
c2d5cc5 [Sean Owen] Update plugins and Maven version; use variables consistently across Maven/SBT to define dependency versions that should stay in step.
SPARK-1349: spark-shell gets its own command history

Currently, spark-shell shares its command history with scala repl.

This fix is simply a modification of the default FileBackedHistory file setting:
https://github.com/scala/scala/blob/master/src/repl/scala/tools/nsc/interpreter/session/FileBackedHistory.scala#L77

Author: Aaron Davidson <aaron@databricks.com>

Closes #267 from aarondav/repl and squashes the following commits:

f9c62d2 [Aaron Davidson] SPARK-1349: spark-shell gets its own command history separate from scala repl
SPARK-1314: Use SPARK_HIVE to determine if we include Hive in packaging

Previously, we based our decision regarding including datanucleus jars based on the existence of a spark-hive-assembly jar, which was incidentally built whenever "sbt assembly" is run. This means that a typical and previously supported pathway would start using hive jars.

This patch has the following features/bug fixes:

- Use of SPARK_HIVE (default false) to determine if we should include Hive in the assembly jar.
- Analagous feature in Maven with -Phive (previously, there was no support for adding Hive to any of our jars produced by Maven)
- assemble-deps fixed since we no longer use a different ASSEMBLY_DIR
- avoid adding log message in compute-classpath.sh to the classpath :)

Still TODO before mergeable:
- We need to download the datanucleus jars outside of sbt. Perhaps we can have spark-class download them if SPARK_HIVE is set similar to how sbt downloads itself.
- Spark SQL documentation updates.

Author: Aaron Davidson <aaron@databricks.com>

Closes #237 from aarondav/master and squashes the following commits:

5dc4329 [Aaron Davidson] Typo fixes
dd4f298 [Aaron Davidson] Doc update
dd1a365 [Aaron Davidson] Eliminate need for SPARK_HIVE at runtime by d/ling datanucleus from Maven
a9269b5 [Aaron Davidson] [WIP] Use SPARK_HIVE to determine if we include Hive in packaging
SPARK-1154: Clean up app folders in worker nodes

This is a fix for [SPARK-1154](https://issues.apache.org/jira/browse/SPARK-1154).   The issue is that worker nodes fill up with a huge number of app-* folders after some time.  This change adds a periodic cleanup task which asynchronously deletes app directories older than a configurable TTL.

Two new configuration parameters have been introduced:
  spark.worker.cleanup_interval
  spark.worker.app_data_ttl

This change does not include moving the downloads of application jars to a location outside of the work directory.  We will address that if we have time, but that potentially involves caching so it will come either as part of this PR or a separate PR.

Author: Evan Chan <ev@ooyala.com>
Author: Kelvin Chu <kelvinkwchu@yahoo.com>

Closes #288 from velvia/SPARK-1154-cleanup-app-folders and squashes the following commits:

0689995 [Evan Chan] CR from @aarondav - move config, clarify for standalone mode
9f10d96 [Evan Chan] CR from @pwendell - rename configs and add cleanup.enabled
f2f6027 [Evan Chan] CR from @andrewor14
553d8c2 [Kelvin Chu] change the variable name to currentTimeMillis since it actually tracks in seconds
8dc9cb5 [Kelvin Chu] Fixed a bug in Utils.findOldFiles() after merge.
cb52f2b [Kelvin Chu] Change the name of findOldestFiles() to findOldFiles()
72f7d2d [Kelvin Chu] Fix a bug of Utils.findOldestFiles(). file.lastModified is returned in milliseconds.
ad99955 [Kelvin Chu] Add unit test for Utils.findOldestFiles()
dc1a311 [Evan Chan] Don't recompute current time with every new file
e3c408e [Evan Chan] Document the two new settings
b92752b [Evan Chan] SPARK-1154: Add a periodic task to clean up app directories