bundle gulp task

Use webpack to create two UMD bundles - one of just ionic that
expects Angular2 to be an external module, the other that includes
zone.js, reflect-metadata, and angular2 as well.

scripts/npm/ionic.webpack.config.js

@@ -0,0 +1,16 @@
+module.exports = {
+  entry: [
+    "es6-shim/es6-shim.min.js",
+    "./dist/ionic.js"
+  ],
+  output: {
+    path: 'dist/bundles',
+    filename: 'ionic.js',
+    libraryTarget: 'umd'
+  },
+  externals: [
+    'angular2/angular2',
+    'angular2/router',
+    'angular2/http'
+  ]
+};