Don't save svg, return rendering at api endpoint.

One less layer of needless indirection is nice, but I did this so that I could
use this app on heroku, which does not allow saving files to the file-system.

laundry_app/static/js/laundry.js

@@ -27,7 +27,7 @@ function update_charts(selected) {
         request = $.ajax({
             url: '/ajax/current/' + halls[selected]
         }).done(function (result) {
-            svg.attr('src', result);
+            svg.attr('src', '/ajax/current/' + halls[selected]);
             $('#loading').remove();
             console.log(svg);
             $('.current-chart').append(svg);