made school data display a little more robust.

removed html from javascript code.
added a max limit to the number of schools displayed.
fixed schools from being added more than once.
added ability to remove school from list on click of school name
fixed panel to only display when a school has been clicked on.
added css to support above.
fixed an id in the html.
using Solomon’s approach with d3.format() for numerical displays.
removed two functions that are now unused.