Roles and user management

• Create a Seller role
• Create a Buyer group
• Add a role to a group
• Disable a role
• Schedule disabling a role
• Enable a role
• Combine two (or more) separate roles into one group
• Split role from group
• Delete a role
• Change user's role
• Enable users
• Disable users
• Remove users
• Change user's Q&A role
• The users in the Vault can't access it