fix webpack dependency in package.json

Author: KarlAmort

package.json

@@ -18,7 +18,7 @@
     "stream-cache": "~0.0.1",
     "strip-ansi": "^3.0.0",
     "supports-color": "^3.1.1",
-    "webpack": ">=2.0.3-beta <3",
+    "webpack": ">=2.0.7-beta <3",
     "webpack-dev-middleware": "^1.4.0",
     "yargs": "^3.32.0"
   },