Tracking spec level support

[brianjmiller]

Just opening this issue as clearing house for what is and isn't in yet towards spec compliance.

Requirements:

• [x] Bump version list
• [x] Context Activities as arrays
• [ ] deprecated 'voided'
• [x] Add Statement 'version' property
• [ ] Query API (authoritative removal, mode expansion)
• [x] Fetch voided statements
• [ ] Anonymous Groups
• [x] Document merge/partial updates (State, Activity Profile, Agent Profile)
• [x] Statement attachments
• [ ] Statement signing
• [ ] Fetch of URL related items