improved shredding

- shredder is now sending POST requests to the localhost:5000 (rather
than simply writing out classifieds to standard output)
- webserver is receiving the processing the POST request from the
shredder and merging it with a consitent approach to standard selling
- webserver is filtering out duplicates (selling of items through
website now generates a guid, shredder now sends through the id of the
item for uniqueness)
- webserver now sends back some reason around the success of the
submission (either failed OR success)