Use JSPM for frontend JS modules

static/js/colors.js

@@ -0,0 +1,18 @@
+export default function mixColors (colors) {
+  var rgb = colors.map(function (color) {
+    var r = color.substr(1, 2)
+      , g = color.substr(3, 2)
+      , b = color.substr(5, 2);
+
+    return [parseInt(r, 16), parseInt(g, 16), parseInt(b, 16)];
+  });
+
+  var result = [ 0, 0, 0 ];
+  for (var i = 0, l = rgb.length; i < l; i++) {
+    result[0] += rgb[i][0] / l;
+    result[1] += rgb[i][1] / l;
+    result[2] += rgb[i][2] / l;
+  }
+
+  return '#' + result[0].toString(16) + result[1].toString(16) + result[2].toString(16);
+}