Confusing disparity with Facebook OAuth

[glebec]

Facebook uses a clientId in the strategy, but an APP_ID in the production environment variable. See https://github.com/FullstackAcademy/fsg/blob/master/generated/server/env/production.js#L18. While students should notice the difference and put the right vars in Heroku, it is pretty easy to overlook this as it is similar but not identical to the Google variable names.

Not sure why it is coded in as APP_ID — is it to match some Facebook dev tool verbiage? An oversight? Worth looking into to see if it wouldn't be less confusing standardized to CLIENT_ID.