Explicitly specifying the complete URL for resource Location in POSTS

Instead of relying on Werkzeug or Flask to 'complete' the URL
from the URI reference currently provided, this explicitly specifies
the complete URL.  This is laying the foundation for returning
complete URLs in other places as well.
Fields are not returned from API as full URLs

I modified the code so that instead of returning URI references, a
full URL is now returned from the API.  This makes it consistent
with what is returned in the Location header during a POST request.