Merge pull request #27 from SimplePEG/greenkeeper/webpack-4.0.0

Update webpack to the latest version 🚀

Author: obenjiro

Diff for: package.json

@@ -36,7 +36,7 @@
     "mocha": "^5.0.0",
     "mocha-lcov-reporter": "^1.2.0",
     "recursive-readdir-sync": "^1.0.6",
-    "webpack": "^3.5.2",
+    "webpack": "^4.0.0",
     "mockery": "^2.1.0"    
   }
 }