Added listen and virtualhost for port 8443

Port 8443 allows backchannel communication between SP's and IdP's and
adding these capabilities was necessary to enable this.
Removed redundant ssl configuration

SSL configuration that is made redundant by the ssl.conf.include file
has now been removed, and replaced with an include directive. This
eliminates needless repetition and increases code clarity.
Added location to credentials

SSLCertificateFile and SSLCertificateKeyFile settings have been re-added. This
allows apache to find the required credentials.
Merge pull request #68 from ausaccessfed/feature/backchannel-port

Added backchannel communication
Resolves #67