Bumps minimum node engine to 8+ (#4474)

* Use node 8 as development environment

* fixup! Use node 8 as development environment

* bump node to 8.10

* Targets node 8 for everything

* Run npm install so lock file is up to date

* Use push adapter v3

* Deflake a test on ParseUser

* Adds slight delay after logout

* Ensure we wait even if call fails

* Use node carbon

Dockerfile

@@ -1,4 +1,4 @@
-FROM node:boron
+FROM node:carbon
 
 RUN mkdir -p /parse-server
 COPY ./ /parse-server/