firebase api absent from main file in branch 11

[victorkane]

First of all, thanks so much for this great video tutorial.

Working through, I see errors while on branch 11-signup, since the following dependency is actually absent from the top of the main.js form:

import * as firebase from 'firebase'

so invocation of firebase gives error.

This is of course corrected in the next branch, just fyi.

Thanks again, for great video on vuetify (so few things out there right now).