Fixes applied to the model classes to avoid an "undefined constant" error
and changes made to the application to handle image files differently
(added an additional handler to the Razor::WebService::App class to catch
requests for files from an image ISO and handle them there, where we have
easy access to the Rack::Response class).  Finally, added some test code
that uses the "rufus-scheduler" gem to instantiate a thread that cleans
up inactive nodes and cleaned up a few typos and copy-and-paste errors
in the Razor::WebService::Policy::APIv1 class