chore(package): update geckodriver to version 1.8.1 (#86)

Author: greenkeeper[bot]

package.json

@@ -19,7 +19,7 @@
     "eslint-plugin-mocha": "4.11.0",
     "eslint-plugin-promise": "3.5.0",
     "fx-runner": "1.0.7",
-    "geckodriver": "1.8.0",
+    "geckodriver": "1.8.1",
     "karma": "1.7.1",
     "karma-coverage": "1.1.1",
     "karma-coveralls": "1.1.2",