configure width/height settings

[deanmalmgren]

The width of the bars (80px) and the height of each chart (100px) are currently hardcoded into catcorr.js. It would be nice if these were customizable, probably following the convention proposed in #29 with something like this:

var cc = catcorr("#selector", data, {
    bar_width: 80,
    chart_height: 100,
});