Multiple changes. Added property to SleepItem model to store as a double the number of seconds slept. This is now the value displayed on the table (for error checking—will revert to pretty NSString before deployment). Implemented basic core plot framework to draw rudimentary line graph of points in entries. StatsVS now reverses entries when loading to draw in order. Draws basic line graph.

TODO: Must fix table view. Must add a way to calculate the time slept in hours, not in seconds. Must fix look of chart.