Removed unused properties
Better docstrings
Replaced JSONResponse(404) with abort(404)

When a 404 was encountered, the JSONResponse object was trying to be
marshalled. The abort function, on the other hand, raises an Exception,
aborting the execution of the script.
Added converter
Implemented ConverterResource URI.
Convertion docs
Fixed slugify.

The slugify() function should fallback to a random string only when the
generated slug is an empty string. Instead, it was always using that method.