Add es6-promise polyfill to webpack config

package.json

@@ -37,6 +37,7 @@
     "webpack": "^1.12.13"
   },
   "dependencies": {
+    "es6-promise": "^3.3.0",
     "moment": "^2.8.4",
     "preact": "^4.5.1",
     "preact-compat": "^1.7.0",

webpack.config.js

@@ -1,3 +1,6 @@
+// Support for Node 0.10
+// See https://github.com/webpack/css-loader/issues/144
+require('es6-promise').polyfill();
 var _ = require('underscore');
 var path = require('path');
 var sourcemaps = 'inline-source-map';