Data Access Requirements

[ross-weir]

This issue is to keep track of data access queries required to help further model the chaincash data store.

• Get issuer of a note
• Get all notes issued by an agent (required by #26)
  • (should be covered by ^) Get the highest value note issued by agent (required by #26)
• Get total reserves for note (required by #26)
• Get all signers for a note (required by #26)