Feature/1770 new upgrade page

- [ ] Ready to merge

# Todo list
- [ ] Two-step form
- [x] Hide/show github/normal login
- [ ] Backend for the new payment form
- [ ] Handle reg & login errors

# Testing

## Existing user, logged in

- [ ] Fill out form correctly and upgrades
- [ ] Fill out form incorrectly and sees errors

## Existing user, logged out

- [ ] Fills out form, signs in and upgrades
- [ ] Fills out form, failed to sign in
- [ ] Fills out form, signs in, but payment fails (note: user is now logged in)

## New user

- [ ] Fills out form, registers and upgrades
- [ ] Fills out form, failed to register
- [ ] Fills out form, registers, but payment fails (note: user is now logged in)

## Github sign in

- [ ] Goes through github auth as new user, fills out form and upgrades
- [ ] Goes through github auth, but can't link their account to JS Bin account