#3 scponly jail umask

[Manfred]

open ssh supports the -u 0002 umask option for the sftp-server setting, but scopnly only validates sftp-server without arguments so the setup fails.
The patch adds the -u argument to the allowed list.

sshd_config:
> # override default of no subsystems
> Subsystem sftp /usr/libexec/sftp-server -u 0002

[Manfred]

umask fix