Don't disable SSH host key checking by default for any host.

If I want that behavior I would be explicit about it and use the `unssh`
alias instead.

.ssh/config.d/20_endless

@@ -21,8 +21,6 @@ Host 10.17.*.* *.dev.endlessm.com *.dev.endlessm-sf.com
 ProxyCommand ssh vpn-router.uw1.endlessm.com -W %h:%p
 
 Host 172.31.*.* 10.*.*.* *.endlessm-sf.com
-UserKnownHostsFile /dev/null
-StrictHostKeyChecking no
 ProxyCommand ssh openvpn.endlessm.com -W %h:%p
 
 Host 172.31.*.* 10.*.*.* *.endlessm.com *.endlessm-sf.com endlessm.com

.ssh/config.d/90_ec2

-
-# vim:ft=sshconfig
-# Disable SSH host key checking for EC2 instances.
-
-Host  *.compute-1.amazonaws.com
-UserKnownHostsFile /dev/null
-StrictHostKeyChecking no