chore(package): update webpack to version 4.26.0

Closes #60

package.json

@@ -30,6 +30,6 @@
     "istanbul": "~0.4.5",
     "mocha": "~5.2.0",
     "pre-commit": "~1.2.0",
-    "webpack": "~4.24.0"
+    "webpack": "~4.26.0"
   }
 }