Add: User Notes

[hmrtn]

The db schema needs to allow the addition of user notes to a party document. Ideally, every candidate in an election has the option of uploading a small blurb of their name/notes. This will provide some permissioned context that is required in a party.

The user should also have the option of editing the blurb at any point. Each blurb should be signed.

• Add capability upload a note to each respective candidate, from the candidate
• Note editing capability (from candidate)
• Signature verification of notes