Meteor should be able to handle babel.config.js

[ToyboxZach]

Right now meteor only handles .bablerc but there are a bunch of ways to define the config for babel that should be supported: https://babeljs.io/docs/config-files

My problem that I'm trying to fix is that I want to have babel compile my app differently based on an environment variable. Its technically possible with .babelrc env field, but for anything more complex than a switch statement between values its becomes very cumbersome and annoying. Supporting babel.config.js instead would make my config file much easier to manage