Commit of Draft Peer Assignment 1.

All questions have been addressed in one form or another, although several issues remain. Consider more elegant methods of programming.
Time Series plot clean up, and formatting of figure output
Code cleanup. Report mean steps per day using inline code chunk, and cleanup of steps per day histogram axes labels.
Change y-axis label for mean step interval plot
Modify reporting of check for imputed dataset
Correct spelling error in text in final question and add comment to WeekendClassifier() funtion.