Changes

Message deletion days validation on member ban (#848)
* Message deletion days validation on member ban
 Signed-off-by: Fabricio20 <fabricio20r@hotmail.com>

* Use generic check instead of creating a new method
 Signed-off-by: Fabricio20 <fabricio20r@hotmail.com>

* Abide by RFC 2119 on exception message
 Signed-off-by: Fabricio20 <fabricio20r@hotmail.com>

* Fix documentation on missing methods, add check for ban by id.
 Signed-off-by: Fabricio20 <fabricio20r@hotmail.com>

* Fix documentation issues on ban methods
 Signed-off-by: Fabricio20 <fabricio20r@hotmail.com>
 (commit: 8b478d2)