Use libwrap with *channel RPC services

[scottsakai]

These services get dropped on random ports, making it hard to apply firewall rules. Use libwrap / tcpd to offer some additional security.

Also:

• Added syslog messages to sec_channel_server because nothing sees stderr/stdout.
• Remove extraneous reference to hexdump.h

[scottsakai]

Also added input validation checks for kickstart.cgi, addressing some SQLi issues.