implement all REST services

all REST srvice endpoints are implemented
you can HEAD, GET, POST, PUT and DELETE
although you cannot delete objects in Swift as a result of a DELETE, but you can do any other "RESTful" thing there
fixed the following:
- better precedense of headers, usually needed for HEAD, which should sometimes output same headers as GET but with no body
- status handling, `message/cgi` and `message/http` responses should be able to overwrite HTTP status

and as a consequence you can now shoot yourself in the foot by using `Content-Length` with no content and other strange constructs