First draft of program.

The program downloads the datafile from the web, extracts it, and reads the
data into a dataframe.
Added code to...

-Convert the date and time columns into a single datetime column
-Subset the total data to values for 02/01/2007 and 02/02/2007
-Create a histogram for the Global_active_power column
-Fill the bars in the histogram with red and apply appropriate titles and labels
Merge https://github.com/james-shields/ExData_Plotting1