Upgrade mocha

Author: jakezatecky

package.json

@@ -51,7 +51,7 @@
     "gulp-sass": "^3.0.0",
     "gulp-scss-lint": "^0.5.0",
     "jsdom": "^11.0.0",
-    "mocha": "^3.0.2",
+    "mocha": "^4.0.1",
     "react": "^16.0.0",
     "react-dom": "^16.0.0",
     "react-test-renderer": "^16.0.0",