email notification

Release 241

New: Email notification for missed chat messages
New: Email notification for missed @ mentions in chat messages
New: Add custom link to main menu
New: Add custom field to member profile and optionally hide it from members
New: API endpoints for members – GET: list of members, PUT: update member, DELETE: remove member from organization or group
Update: API endpoint for groups – PUT: update group
Fix: Chat bugs
Fix: SSL error