The default user and password are used for anonymous FTP by default.
This patch adds support for an explicit user name and password in an FTP
URI:

    imgfetch ftp://user:password@server.com/path/to/file

Edited-by: Stefan Hajnoczi <stefanha@gmail.com>.  Bugs are my fault.

Signed-off-by: Marty Connor <mdc@etherboot.org>