WIP: dGrants Protocol specification

[phutchins]

This PR intends to get us a solid outline and start to the protocol specification for dGrants and its pluggable components.

This document is being edited here: https://hackmd.io/@TsHJ2al1Th2MarDFDKpV7g/H1hcQmUzF

This document should:

• Provide a high level description of each of the components
• Identify the core components of dGrants (Grant Registry & Grant Rounds)
• Identify how a UI should be built on top of the Grant Registry and Grant Rounds
• Identify the optional dGrants modules (curation, sybil resistance, matching)
• Describe the format of each of the data structures and examples (GrantRegistry, Grant, GrantRound, etc...)
• Identify where and how each of the components fit together
• Clearly specify each components interface and how to interact with it