chore(package): enable greenkeeper

Author: niieani

package.json

@@ -7,7 +7,8 @@
     "test": "TS_NODE_FAST=true TS_NODE_NO_PROJECT=true ava",
     "prepublish": "typings install",
     "build": "rimraf dist && tsc -p .",
-    "semantic-release": "npm run build && semantic-release pre && npm publish --access=public && semantic-release post"
+    "semantic-release": "npm run build && semantic-release pre && npm publish --access=public && semantic-release post",
+    "postpublish": "greenkeeper-postpublish"
   },
   "repository": {
     "type": "git",