curl -u foo:XXXX http://localhost:5984/_session
{"ok":true,"userCtx":{"name":"foo","roles":[]},"info":{"authentication_db":"_users","authentication_handlers":["cookie","default"],"authenticated":"default"}}

curl http://localhost:5984/_session -H
    'Content-Type:application/x-www-form-urlencoded' -d 'name=foo&password=XXXX'
{"error":"unauthorized","reason":"Authentication required."}

curl http://localhost:5984/_session -H 'Content-Type:application/x-www-form-urlencoded' -d 'name=foo&password=XXXX'
{"ok":true,"name":"foo","roles":[]}

[chttpd]
authentication_db = _users
require_valid_user = true