Fix links and make things a bit prettier.

easier to read.

Adds a "docs" directory containing existing Spark documentation and doc build instructions

docs/README.md to describe use of Jekyll, and renmaed things to make them
more consistent with the lower-case-with-hyphens convention.

which can be compiled via jekyll, using the command `jekyll`. To compile
and run a local webserver to serve the doc as a website, run
`jekyll --server`.

Spark HTTP FileServer

Conflicts:
	core/src/main/scala/spark/SparkContext.scala

Log entire exception (including stack trace) in BlockManagerWorker.

logError API.

A general fileserver for both JARs and regular files.

Add shutdown hook to Executor Runner and execute code to shutdown local cluster in Scheduler Backend

Simulating a Spark standalone cluster locally

Add shutdown hook to Executor Runner and execute code to shutdown local cluster in Scheduler Backend