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.
Couple of clarifications

1. I guess we want to append to the file in `~/.Rprofile` and not in the current working directory ?

2. Since the SparkR install path used here is the one used in the SparkR setup script, what do you think about merging this with the other script ? (i.e. adding the IDE installation bits to the end of that script).