[payment agent] Strawman proposal for document structure

Here are a few incomplete thoughts about what the structure for the
Payment Agent document could be.

1. We may want to take a role based approach where we clearly
   identify the roles that a payment agent may be playing
   (payer / payee / merchant / customer / etc.).
2. For each role, we list a number of features that the role
   requires to play its part in the overall architecture.

Here's a proposed subsection of the Table of Contents that we can
discuss on the call tomorrow:

* Payment Agent
  * Core Features
    * Identity/Credential Management
    * Digital Signatures
    * Linked Data
  * Payer (Customer) Features
    * Payment Instrument Management
    * Payer Authentication
    * Digital Receipt Storage
    * Coupon / Loyalty Management
    * Payee Communication
    * Payment Processor Communication
  * Payee (Merchant) Features
    * Offer of Sale / Invoice Generation
    * Digital Receipt Issuance
    * Refund Initiation
    * Payer Communication
    * Payment Processor Communication
  * Payment Processor Features
    * Payer / Payee Authentication
    * Settlement Network Communication
    * Payee Communication
    * Payer Communication

Another approach is to try the phase-based approach, which I hope to get
around to in the next few days.

-- manu

-- 
Manu Sporny (skype: msporny, twitter: manusporny, G+: +Manu Sporny)
Founder/CEO - Digital Bazaar, Inc.
blog: The Marathonic Dawn of Web Payments
http://manu.sporny.org/2014/dawn-of-web-payments/