Fixed wrong namespaces
New error for missing route
Changed Error exception for not found route to MissingRouteError
Changed error handling on start() to use messagehandler to display error
message after redirect to a target definable by Error exception. 
See changes in: Web\Framework\Lib\Error
Changed error creation to take care of admin/user messages. 

- To use this dual message system, simply return an indexed array where
the first message is the admin and the second one the message to show
normal users.
- Changed the way a trace will be appended on request.
- Added methods to set and get an redirect url