This makes sure that whenever a Webdav call is done through Ajax, if the
session has expired, it will not send back a challenge but a simple 401
response. Without this fix, the default code would send back a challenge
and trigger the browser's basic auth dialog.
Introduce a new property "oc:fileid" to return the internal file id.
This is because the original "oc:id" property is a compound and it is
not possible to extract the real id without knowing the instance id. The
instance id is not available to external clients.
WebDAVFS as used by Finder requires a Class 2 compatible WebDAV server. This change introduces a fake locking provider which will simply advertise Locking support when a request originates from WebDAVFS. It will also return successful LOCK and UNLOCK responses.