Ability to hook into exception handler

[oliverheywood451]

This is a placeholder for a thought that's still developing.

How can Catalyst support useful logging of API error responses? It should not depend on any one storage option. But it could provide some means to hook into GlobalExceptionHandler and do custom logging without totally replacing that class.

In azure, application insights is pretty good, but is missing stack traces. Crhist is investigating if that can be added.