[paymentrequest] Added initial spec drafts and architecture overview. (#24)

I've created initial drafts based on the explainer document to give us something to start with. There are lots of open issues called out, linking to the appropriate GitHub issue where possible. I've tried to make sure that all relevant GitHub issues in this repo are linked from the appropriate section.
You can view, comment on, or merge this pull request online at:

  https://github.com/WICG/paymentrequest/pull/24

-- Commit Summary --

  * Added initial spec drafts and architecture overview.

-- File Changes --

    A specs/arch.svg (440)
    A specs/architecture.html (224)
    A specs/method-identifiers.html (80)
    A specs/paymentrequest.html (574)

-- Patch Links --

https://github.com/WICG/paymentrequest/pull/24.patch
https://github.com/WICG/paymentrequest/pull/24.diff

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Reply to this email directly or view it on GitHub:
https://github.com/WICG/paymentrequest/pull/24