Support Windows domain accounts for CIFS+Telnet with the pre-2000 Windows domain user syntax (again)

[vpartington]

Overthere 1.x supported using Windows domain accounts for CIFS+Telnet connections using the pre-2000 Windows domain user syntax, i.e. DOMAIN\USER. That support was disabled in Overthere 2.0.0 because of a validation added to ensure the new style Windows domain user syntax, i.e. USER@FULL.DOMAIN, was used for Kerberos authentication.

Re-enable that again.