Issue#28 Added index.js to support import for dc.leaflet

Author: doshisunny

index.js

@@ -0,0 +1,7 @@
+d3 = require("d3");
+crossfilter = require("crossfilter2");
+dc = require("dc");
+leaflet = require('leaflet');
+leaflet.markercluster = require('leaflet.markercluster');
+
+module.exports = require("./dc.leaflet");