Include reference to twitter/chill in tuning docs

Author: Andrew Ash <andrew@andrewash.com>

Closes #647 from ash211/doc-tuning and squashes the following commits:

b87de0a [Andrew Ash] Include reference to twitter/chill in tuning docs
Graph primitives2

Hi guys,

I'm following Joey and Ankur's suggestions to add collectEdges and pickRandomVertex. I'm also adding the tests for collectEdges and refactoring one method getCycleGraph in GraphOpsSuite.scala.

Thank you,

semih

Author: Semih Salihoglu <semihsalihoglu@gmail.com>

Closes #580 from semihsalihoglu/GraphPrimitives2 and squashes the following commits:

937d3ec [Semih Salihoglu] - Fixed the scalastyle errors.
a69a152 [Semih Salihoglu] - Adding collectEdges and pickRandomVertices. - Adding tests for collectEdges. - Refactoring a getCycle utility function for GraphOpsSuite.scala.
41265a6 [Semih Salihoglu] - Adding collectEdges and pickRandomVertex. - Adding tests for collectEdges. - Recycling a getCycle utility test file.
For SPARK-1082, Use Curator for ZK interaction in standalone cluster

Author: Raymond Liu <raymond.liu@intel.com>

Closes #611 from colorant/curator and squashes the following commits:

7556aa1 [Raymond Liu] Address review comments
af92e1f [Raymond Liu] Fix coding style
964f3c2 [Raymond Liu] Ignore NodeExists exception
6df2966 [Raymond Liu] Rewrite zookeeper client code with curator
SPARK-1053.  Don't require SPARK_YARN_APP_JAR

It looks this just requires taking out the checks.

I verified that, with the patch, I was able to run spark-shell through yarn without setting the environment variable.

Author: Sandy Ryza <sandy@cloudera.com>

Closes #553 from sryza/sandy-spark-1053 and squashes the following commits:

b037676 [Sandy Ryza] SPARK-1053.  Don't require SPARK_YARN_APP_JAR
SPARK-1078:  Replace lift-json with json4s-jackson.

The aim of the Json4s project is to provide a common API for
Scala JSON libraries.  It is Apache-licensed, easier for
downstream distributions to package, and mostly API-compatible
with lift-json.  Furthermore, the Jackson-backed implementation
parses faster than lift-json on all but the smallest inputs.

Author: William Benton <willb@redhat.com>

Closes #582 from willb/json4s and squashes the following commits:

7ca62c4 [William Benton] Replace lift-json with json4s-jackson.
SPARK-1135: fix broken anchors in docs

A recent PR that added Java vs Scala tabs for streaming also
inadvertently added some bad code to a document.ready handler, breaking
our other handler that manages scrolling to anchors correctly with the
floating top bar. As a result the section title ended up always being
hidden below the top bar. This removes the unnecessary JavaScript code.

Author: Matei Zaharia <matei@databricks.com>

Closes #3 from mateiz/doc-links and squashes the following commits:

e2a3488 [Matei Zaharia] SPARK-1135: fix broken anchors in docs
SPARK-1115: Catch depickling errors

This surroungs the complete worker code in a try/except block so we catch any error that arrives. An example would be the depickling failing for some reason

@JoshRosen

Author: Bouke van der Bijl <boukevanderbijl@gmail.com>

Closes #644 from bouk/catch-depickling-errors and squashes the following commits:

f0f67cc [Bouke van der Bijl] Lol indentation
0e4d504 [Bouke van der Bijl] Surround the complete python worker with the try block
Removed reference to incubation in README.md.

Author: Reynold Xin <rxin@apache.org>

Closes #1 from rxin/readme and squashes the following commits:

b3a77cd [Reynold Xin] Removed reference to incubation in README.md.