build(npm): fixed webpack version

2.1.0-beta.22 works, upgrading every release is time consuming.
Waiting for a stable version.

package.json

@@ -143,7 +143,7 @@
     "tslint": "^3.15.0",
     "tslint-loader": "^2.1.3",
     "typings": "^1.3.1",
-    "webpack": "^2.1.0-beta.22",
+    "webpack": "2.1.0-beta.22",
     "webpack-dev-server": "^2.1.0-beta.0",
     "webpack-md5-hash": "^0.0.5",
     "webpack-merge": "^0.14.0"