Author: Reynold Xin <rxin@apache.org>

Closes #2 from rxin/docs and squashes the following commits:

08bbd5f [Reynold Xin] Removed reference to incubation in Spark user docs.

The current doc hints spark doesn't support accumulators of type `Long`, which is wrong.

JIRA: https://spark-project.atlassian.net/browse/SPARK-1117

Author: Xiangrui Meng <meng@databricks.com>

Closes #631 from mengxr/acc and squashes the following commits:

45ecd25 [Xiangrui Meng] update accumulator docs

https://spark-project.atlassian.net/browse/SPARK-1105

fix site scala version error

Author: CodingCat <zhunansjtu@gmail.com>

Closes #618 from CodingCat/doc_version and squashes the following commits:

39bb8aa [CodingCat] more fixes
65bedb0 [CodingCat] fix site scala version error in doc

Also, replace the last reference to it in the docs.

This fixes SPARK-1026.

This reverts commit 79b20e4d, reversing
changes made to 7375047d.

val => var

Also changed uses of "job" terminology to "application" when they
referred to an entire Spark program, to avoid confusion.

* RDD, *RDDFunctions -> org.apache.spark.rdd
* Utils, ClosureCleaner, SizeEstimator -> org.apache.spark.util
* JavaSerializer, KryoSerializer -> org.apache.spark.serializer

This commit makes Spark invocation saner by using an assembly JAR to
find all of Spark's dependencies instead of adding all the JARs in
lib_managed. It also packages the examples into an assembly and uses
that as SPARK_EXAMPLES_JAR. Finally, it replaces the old "run" script
with two better-named scripts: "run-examples" for examples, and
"spark-class" for Spark internal classes (e.g. REPL, master, etc). This
is also designed to minimize the confusion people have in trying to use
"run" to run their own classes; it's not meant to do that, but now at
least if they look at it, they can modify run-examples to do a decent
job for them.

As part of this, Bagel's examples are also now properly moved to the
examples package instead of bagel.

Also warns if spark.cleaner.ttl is not set in the version where you pass
your own SparkContext.

ordering, so the reduce function must also be commutative.

Made StorageLevel constructor private, and added StorageLevels.create() to the Java API. Updates scala and java programming guides.

- Edited quick start and tuning guide to simplify them a little
- Simplified top menu bar
- Made private a SparkContext constructor parameter that was left as
  public
- Various small fixes

also adding the version to the navbar so it is easy to tell which
version of Spark these docs were compiled for.

throughout the docs: SPARK_VERSION, SCALA_VERSION, and MESOS_VERSION.

To use them, e.g. use {{site.SPARK_VERSION}}.

Also removes uses of {{HOME_PATH}} which were being resolved to ""
by the templating system anyway.