Update @google-cloud/common to the latest version 🚀 (#57)

* fix(package): update @google-cloud/common to version 0.18.0

* Update package.json

Author: greenkeeper[bot]

packages/google-cloud-vision/package.json

@@ -58,7 +58,7 @@
     "test": "repo-tools test run --cmd npm -- run cover"
   },
   "dependencies": {
-    "@google-cloud/common": "^0.17.0",
+    "@google-cloud/common": "^0.18.2",
     "async": "^2.0.1",
     "extend": "^3.0.0",
     "google-gax": "^0.16.0",