WIP BibCheck: port to pu

Work so far done is regarding a stable configuration format interface to work towards an API, using manager.py and utilizing workflows.
The dependency problem is that `flask-ext` does not expose the error type that it handles (even if behind the scenes). We could make the error as useful as we wish it to be, but they put this burden on us.

The real issue that stems from this discussion is that `type=` functions should only break when user input is broken, so the developer should be able to reproduce unforeseen errors by typing in the same input.

These being said, I will move logic that does not belong in `type=` out of them and remove the dependency.