Members Controller: Manage records of registered users in a MySQL

This class can be used to manage records of registered users stored in a MySQL database. It can:

- Create new user records
- Verify an user password and starts a logged user session
- End a logged user session
- Check if an account exists with a given user name
- Check if an user has certain permissions
- Retrieve user information by user name, e-mail or id or some other attribute
- Delete an user
- Update an user record