Add support for move operation

This implements non-recursive move for S3 and WebDAV.
historically, I think you can simply write as:
201: 'OK', 204: 'OK', ...
for Object literals, where each keys are string.
And if you specify a number to the object, it's converted into a string.  So you don't have to cast like this here, and you can omit the quote for keys in line 16-24.  I believe that's more concise.