[winswitch] Secure TCP mode with --password-file

[John Smith]

Hi,

Recently, I have upgrade xpra from 0.14.x to 0.15.0 for my server (trusty)
. And now I can't use --password-file option to secure tcp mode as before.
Server use --password-file=<path/to/file/contains/password>, but client
don't need to use --password-file to attach . I think the problems is xpra
for server. If this is a bug, I will file a ticket about this.
Thanks.