This is an initial spike on how the middleware might be included into
the system. It is inspired/copied from GIN, so I still have to work out,
how to make it nicer than it is at the moment.
What is currently missing is Aborting and the addRoute function looks
very ugly.
To handle errors correctly the post controller needed some rework. Now
instead of single functions running all around the place, there is one
function collecting the data needed and raising errors when needed.
For that to work, the controller class can now return more classes to
keep the chain going. Unless a class is returned, it will call the
renderer.
