v2.0.0

• [breaking change] For Firestore-triggered functions, snapshot.createTime, snapshot.updateTime, snapshot.readTime, and any timestamp values in snapshot.data() are now [Firestore Timestamp](https://cloud.google.com/nodejs/docs/reference/firestore/0.15.x/Timestamp#properties) objects.
• Support Node.js 8 runtime. To deploy your functions to Node.js 8, add "engines": {"node": "8"} to functions/package.json. You will need firebase-tools >=v4.0.0.
• Support selection of regions for your functions through the functions.region method. Learn more in the [Firebase Documentation](https://firebase.google.com/docs/functions/locations). You will need firebase-tools >=v4.0.0.
• Support configuration of timeout and memory allocation through the functions.runWith method. Learn more in the [Firebase Documentation](https://firebase.google.com/docs/functions/manage-functions#set_timeout_and_memory_allocation). You will need firebase-tools >=v4.0.0.