chore(package): update mocha to version 5.0.3

Closes #32

Author: greenkeeper[bot]

package.json

@@ -75,7 +75,7 @@
     "expect-react-shallow": "~1.2.1",
     "gulp": "3.9.1",
     "gulp-gh-pages": "0.5.4",
-    "mocha": "~3.1.2",
+    "mocha": "~5.0.3",
     "postcss-modules-extract-imports": "~1.0.0",
     "postcss-modules-scope": "~1.0.0",
     "react": "^15.3.2"