Apache + Nginx port conflict following source deployment guide

When following the [Deploying a source install](http://docs.ckan.org/en/latest/maintaining/installing/deployment.html) guide it should be noted that Apache and Nginx are conflicting on port 80. The necessary fix requires editing the `/etc/apache/ports.conf` file and changing the `NameVirtualHost` and `Listen` parameters to `8080` and not `80`