Create custom ErrorMiddleware to support Rest about framework HOT 2 CLOSED

Hello, there are already possibilities to achieve this functionality:

• Throw an exception that implements \Igni\Http\Exception\HttpException
• Add custom middleware by $app->use() or register module implementing \Igni\Http\MiddlewareProvider

I was also thinking about extending ErrorMiddleware and replacing it with one defined by user if it gets registered. But this will destroy modules that are implementing OnErrorListener interface.

from framework.

I have also added PR with upgraded docs and improved current http exception handling #20

from framework.