Disable serving static files from the default wsgi_app

Added the wsgi_dev_app which does serve static files.
Fixed bug preventing deserialisation of date strings
Fixed bug in class serialisation
Improved detection of file return types

Prevent misdetection of modules with read function as a file object
Re-enable deserialisation of parameters using json_loaders
Enable nice urls (api v2) for calling methods of classes
Tidy code and use api v2 for class method calls
Bump semvar to 1.2.1