Update dependencies to enable Greenkeeper 🌴 (#18)

* chore(package): update dependencies

* docs(readme): add Greenkeeper badge

README.md

@@ -2,6 +2,8 @@
 
 # [Google Cloud Pub/Sub: Node.js Client](https://github.com/googleapis/nodejs-pubsub)
 
+[![Greenkeeper badge](https://badges.greenkeeper.io/googleapis/nodejs-pubsub.svg)](https://greenkeeper.io/)
+
 [![release level](https://img.shields.io/badge/release%20level-beta-yellow.svg?style=flat)](https://cloud.google.com/terms/launch-stages)
 [![CircleCI](https://img.shields.io/circleci/project/github/googleapis/nodejs-pubsub.svg?style=flat)](https://circleci.com/gh/googleapis/nodejs-pubsub)
 [![AppVeyor](https://ci.appveyor.com/api/projects/status/github/googleapis/nodejs-pubsub?branch=master&svg=true)](https://ci.appveyor.com/project/googleapis/nodejs-pubsub)

package.json

@@ -59,13 +59,13 @@
     "generate-scaffolding": "repo-tools generate all && repo-tools generate lib_samples_readme -l samples/ --config ../.cloud-repo-tools.json"
   },
   "dependencies": {
-    "@google-cloud/common": "^0.13.0",
+    "@google-cloud/common": "^0.15.1",
     "arrify": "^1.0.0",
     "async-each": "^1.0.1",
     "extend": "^3.0.1",
-    "google-auto-auth": "^0.7.1",
+    "google-auto-auth": "^0.8.1",
     "google-gax": "^0.14.2",
-    "google-proto-files": "^0.13.1",
+    "google-proto-files": "^0.14.1",
     "grpc": "^1.7.2",
     "is": "^3.0.1",
     "lodash.merge": "^4.6.0",
@@ -84,7 +84,7 @@
     "ink-docstrap": "^1.3.2",
     "intelli-espower-loader": "^1.0.1",
     "jsdoc": "^3.5.5",
-    "mocha": "^3.5.3",
+    "mocha": "^4.0.1",
     "nyc": "^11.3.0",
     "power-assert": "^1.4.4",
     "prettier": "^1.9.1",