chore(package): update mocha to version 6.2.2

Closes #586

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
         "gulp-istanbul": "1.1.3",
         "gulp-mocha": "6.0.0",
         "istanbul": "0.4.5",
-        "mocha": "6.1.4",
+        "mocha": "6.2.2",
         "parse-comments": "0.4.3",
         "shelljs": "0.8.3",
         "shelljs-nodecli": "0.1.1"