ZS - How To Set Up SSL inc. Client Authentication with Apache 2

Some integration tests require SSL protection of the service endpoint with SSL Client Authentication.
Here's a quick guide how to set up an Apache 2 service on localhost as a SSL terminating reverse proxy to the zusemsg endpoint that runs on <http://localhost:8081/>.

1.   Install Apache 2.
1.   Ensure that mod-proxy is installed and enabled.
1.   In `default-ssl.conf` add the following lines to proxy requests from `https://localhost/zusemsg` to `http://localhost:8081`:

         ProxyRequests off
         ProxyPass /zusemsg/ http://localhost:8081/
         ProxyPassReverse /zusemsg/ http://localhost:8081/
         <Proxy *>
           Order allow,deny
           allow from all
         </Proxy>

1.   Use certificate and key provided in this repository for the TLS connection and add the following directives to `default-ssl.conf`:

         SSLCertificateFile <path/to/repo/ssl/server>/server.localhost.cert.pem
         SSLCertificateKeyFile <path/to/repo/ssl/server>/server.localhost.key.pem
         SSLCertificateChainFile <path/to/repo/ssl/server>/ca-chain.cert.pem

1.   Trust the client certificate with the following directive in `default-ssl-conf`:

         SSLCACertificateFile <path/to/repo/ssl>/trusted-cas-bundle.pem