Separate CAs for client certs and server cert chain

- Modified the VirtualHost screen to make more clear the difference between "server certificate chain" and "client certification authority"
- Modified configuration generation accordingly with proper options (SSLCertificateChainFile for server cert chain, SSLCACertificateFile for client certificates) according to Apache documentation

I ended up needing this as I use pfSense as a HTTPS reverse proxy, with a public server certificate that required specifying the full certificate chain, and client certificate authentication that required validating against my custom CA, therefore requiring both settings in Apache configuration. (Also, SSLCACertificateFile was used where SSLCertificateChainFile would have been appropriate, but this point is now moot)