Added: Exception, NotAllowed and NotFound handlers (Slim app context)

Quote from i-MSCP Github (1.5.3)

Code

1. Added: Exception, NotAllowed and NotFound handlers (Slim app context)
2. Review: Rely only on PSR-11 container interface

Source: https://github.com/i-MSCP/imsc…6fd94638556b72fee7d717ab5