Release v0.4.0 (#182)

Author: JustinBeckwith

cloud-tasks/package.json

@@ -11,7 +11,7 @@
     "test": "mocha system-test"
   },
   "dependencies": {
-    "@google-cloud/tasks": "^0.3.0",
+    "@google-cloud/tasks": "^0.4.0",
     "body-parser": "^1.18.3",
     "express": "^4.16.3",
     "yargs": "^13.0.0"