chore(package): update mocha to version 5.0.0 (#47)

Author: greenkeeper[bot]

package.json

@@ -20,7 +20,7 @@
     "gulp": "^3.9.1",
     "gulp-rename": "^1.2.2",
     "gulp-stylefmt": "^1.1.0",
-    "mocha": "^4.0.1",
+    "mocha": "^5.0.0",
     "nyc": "^11.0.2",
     "postcss-less": "^1.0.2",
     "postcss-reporter": "^5.0.0",