[Cosmo-dev] slight change in 401 responses

[Brian Moseley]

in r4763 i introduced a slight change in how cosmo communicates about
failed authentication.

for protocol (cmp, dav, atom, webcal) requests that include a ticket
as a credential, the response's WWW-Authenticate header is set to
'Ticket'.

for all other protocol requests, the response's WWW-Authenticate
header is set to 'Basic realm="Cosmo Sharing Server"' as before.

there is no change for web ui requests.