Merge branch 'master' into greenkeeper/standard-13.0.1

Author: mrsteele

package.json

@@ -46,8 +46,8 @@
     "babel-preset-es2015": "^6.9.0",
     "babel-register": "^6.9.0",
     "chai": "^4.0.2",
-    "commitizen": "^3.0.0",
-    "cz-conventional-changelog": "^2.0.0",
+    "commitizen": "^4.0.0",
+    "cz-conventional-changelog": "^3.0.0",
     "esdoc": "^1.0.1",
     "mocha": "^5.0.0",
     "nyc": "^14.1.0",