Extract S&P500 data from quandl.com

Extracts S&P500 data up to current day and writes to GSPC.csv file.
R Markdown File: S&P500 csv file creation

R Markdown File for the creation of GSPC.csv from quandl.com data.  Run
in RStudio. install.packages(“knitr”). Click on ‘Knit HTML’ in title
bar above code to run
Merge branch 'Simple-fetch-SP500-data'