- Delete callbacks tests
- Remove some useless code (SendMail), as well as some extra arguments
in certain functions that didn't require them.
- Remove tests for more code that has been moved to default
implementations
- This addresses the problem of having to update multiple times during
one request. It's hard to have a nice interface especially with JWT
because you always end up having to decode the request, encode new
response, write header, then a second write to it comes, and where do
you grab the value from? Often you don't have access to the response
as a "read" structure. So we store it as events instead, and play
those events against the original data right before the response is
written to set the headers.
