Improved window resizing behavior in coloring visualization

This fixes the problem in the coloring visualization where resizing the window moved the nodes away from their edges. I moved edgeCanvas inside the #viz div, and adjusted the CSS as necessary to position it. I did not see any adverse effects on the other visualizations. 

I also changed the degreeHistogram so that the svg resizes when the window resizes, preventing overlap between the graph and the data tables until the window gets very small.