Update management UX flow and wireframe

[brampitoyo]

• Designed payment account modal, which allows user to:
• View payment methods (fixes mozilla/payments-ui#163)
• Add new payment method (fixes mozilla/payments-ui#165)
• Delete payment methods (fixes mozilla/payments-ui#164)
• Designed change subscription page to use the same modal interface as above (fixes mozilla/payments-ui#168)
• Designed page to view transaction receipts and history (fixes mozilla/payments-ui#167)
• When clicking a transaction, a receipt pops up in a modal
• Eliminate manual payment account replacement when an account is deleted

[brampitoyo]

Whoops. Forgot to attach this image to the pull request, which is really the one that fixes all the issues!

I don’t know how to redact, amend and resubmit a pull request. So for now, please merge it. After it’s merged successfully, I will submit a new pull request with the correct new file included.

Sorry!

[andymckay]

Thanks, more pull requests the merrier.