do not lower ssh client security by default

do not lower ssh client security by default

ForwardX11Trusted might be enabled on command line by using -Y instead
of -X, so there's no real need for doing it system-wide(!) default.
Moreover, the rationale behind trusting remote party might be obsolete:
http://dailypackage.fedorabook.com/index.php?/archives/48-Wednesday-Why-Trusted-and-Untrusted-X11-Forwarding-with-SSH.html
Either way, trusting some potentially malicious (especially without
StrictHostKeyChecking) )remote side MUST be conscious decision.