Convert scatterplot and manyboxplots examples to javascript

Remove reliance on coffeescript for the scatterplot and manyboxplots examples. (But perhaps you'd rather include one of these, for the benefit of folks interested in seeing how to implement an ractive with coffeescript?)

Also, fixed a problem in the scatterplot example that arises due to the use of 5 padding values instead of 4, but pulling out the pad.scale parameter as a separate scalePadding param.