Code review comment for lp:~vila/bzr/472161-ftp-utf8

This fix bug #472161 by... simply deleting _remote_path().

It also makes osutils.fancy_rename() more robust against uses with true unicode paths.

I'm not super proud of the trick to disable the unicode tests against medusa,
but I didn't want to make more involved changes for an ftp server that we
don't support with python >= 2.6.

I finally found RFC3640 which clearly states that Unicode paths are to be supported
as utf8-encoded by default.

The RFC mentions the FEAT command to ensure that the server supports UTF8 but I didn't
implement it to avoid the additional roundtrip (we'll find soon enough if UTF8 is not supported).

Feedback and real-world tests welcome !