chore(package): update gh-pages to version 2.1.1

Closes #239

Author: greenkeeper[bot]

package.json

@@ -177,7 +177,7 @@
     "cp-cli": "2.0.0",
     "del-cli": "1.1.0",
     "domino": "2.1.3",
-    "gh-pages": "2.0.1",
+    "gh-pages": "2.1.1",
     "html-loader": "0.5.5",
     "husky": "2.2.0",
     "jasmine-core": "3.4.0",