[SPARK-8124] [SPARKR] Created more examples on SparkR DataFrames

Here are more examples on SparkR DataFrames including creating a Spark Contect and a SQL
context, loading data and simple data manipulation.

Author: Daniel Emaasit (PhD Student) <daniel.emaasit@gmail.com>

Closes #6668 from Emaasit/dan-dev and squashes the following commits:

3a97867 [Daniel Emaasit (PhD Student)] Used fewer rows for createDataFrame
f7227f9 [Daniel Emaasit (PhD Student)] Using command line arguments
a550f70 [Daniel Emaasit (PhD Student)] Used base R functions
33f9882 [Daniel Emaasit (PhD Student)] Renamed file
b6603e3 [Daniel Emaasit (PhD Student)] changed "Describe" function to "describe"
90565dd [Daniel Emaasit (PhD Student)] Deleted the getting-started file
b95a103 [Daniel Emaasit (PhD Student)] Deleted this file
cc55cd8 [Daniel Emaasit (PhD Student)] combined all the code into one .R file
c6933af [Daniel Emaasit (PhD Student)] changed variable name to SQLContext
8e0fe14 [Daniel Emaasit (PhD Student)] provided two options for creating DataFrames
2653573 [Daniel Emaasit (PhD Student)] Updates to a comment and variable name
275b787 [Daniel Emaasit (PhD Student)] Added the Apache License at the top of the file
2e8f724 [Daniel Emaasit (PhD Student)] Added the Apache License at the top of the file
486f44e [Daniel Emaasit (PhD Student)] Added the Apache License at the file
d705112 [Daniel Emaasit (PhD Student)] Created more examples on SparkR DataFrames