Update @google-cloud/common to the latest version 🚀 (#52)

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "system-test": "repo-tools test run --cmd mocha -- system-test/*.js --no-timeouts"
   },
   "dependencies": {
-    "@google-cloud/common": "^0.14.0",
+    "@google-cloud/common": "^0.16.0",
     "arrify": "^1.0.0",
     "concat-stream": "^1.5.0",
     "create-error-class": "^3.0.2",