Ignore data files in version control
Script to download, extract and tidy the data set

Added the load.data.R script that downloads the zipfile with the data,
extracts it to the data directory, and performs tidying operations
to make the data useable by the plotting functions.
Changed column name from Date_time to datetime

Changed the column name for the data table "household.power.consumption"
from Date_time to datetime to better reflect the plots in the assignment.
Correct File-Name information in file header
Code and plot for histogram of Global Active Power

Create a historgram of Global Active Power, the household minute-averaged
active power in kilowatts.