Sink app compilation into Reflex CLI #4
Description
Current reflex serve implementation runs gulp in the app whenever any code changes, which is ok for now.
Eventually, it would be better not to rely on the guest app to use gulp or any build step at all. It will allow us to swap the build implementation underneath as needed and optimise it, since we'll know nothing else happens in the compile process. It will also allow the app devs to use gulp for their own purposes without having to deal with our Gulpfile code.