#9 Support new Kerberos option --krb

[Liam Healy]

Curl now supports Kerberos with a --krb flag:
http://curl.haxx.se/docs/manpage.html

--krb <level>

(FTP) Enable Kerberos authentication and use. The level must be entered and should be one of 'clear', 'safe', 'confidential' or 'private'. Should you use a level that is not one of these, 'private' will instead be used.

This option requires that the library was built with kerberos4 or GSSAPI (GSS-Negotiate) support. This is not very common. Use -V/--version to see if your curl supports it.

If this option is used several times, the last one will be used.

Can this be incorporated into CurlFtpFS?

Thanks,
Liam