Added code to the file storyLine.js in the storyLine widget folder to automatically determine the best unit for each hotspot on the storyline. Originally, all hotspots used days as their units. This improvement was motivated by a TODO comment left in the code. Also, moved the minimum pixels per unit (MIN_PIXELS_PER_UNIT) and the percent of the timeline's width devoted to the margins (TIMELINE_MARGINS) into reusable constants.