Update browserify

Closes GH-5.

Author: greenkeeperio-bot

package.json

@@ -22,7 +22,7 @@
     "mdast-util-to-string": "^1.0.0"
   },
   "devDependencies": {
-    "browserify": "^13.0.0",
+    "browserify": "^14.0.0",
     "esmangle": "^1.0.0",
     "nyc": "^10.0.0",
     "remark": "^6.0.0",