Sysax Multi-Server SSHD DoS

This exploit affects Sysax Multi-Server version 6.10. It causes a
Denial of Service by sending a specially crafted Key Exchange, which
causes the service to crash.
Added some error handling if the connection dies.
Added reference
Removed final debug print statement
Code Review Feedback
made the CLIENTVERSION always include the "SSH-2.0-OpenSSH_5.1p1 " to trigger DoS
Merge remote-tracking branch 'origin/pr/1710' into landing-pr1710
final cleanup for sysax_sshd_kexchange