SparkR Quick-Start and IDE Setup

Includes .md files for a SparkR quick-start tutorial as well as as a short guide to getting Rstudio set up and working with SparkR on the Cloudera VM.

In addition, this commit includes a shell script that handles the Rstudio set-up.
@shivaram Definitely not.  I didn't realize that my pull request would just keep updating until it was accepted.  Sorry about that