Add redirect_uri to stripe_auth

[begedin]

What's in this PR?

I've set urls for all environments. However, to have this work fully, we have to set our redirect uri field on our Stripe dashboard to a comma-separated list of these URls:

"http://localhost:4200/oauth/stripe" - test and dev
"http://www.codecorps.org/oauth/stripe" - production
"http://www.pbqrpbecf-qri.org/oauth/stripe" - remote dev
"http://www.pbqrpbecf.org/oauth/stripe" - staging

I did not make that change since we probably ought to merge this first.

References

Fixes #504