Add initial version of Dockerfile. This sets up a Docker image with the following properties:
 - Based on CentOS 6 image from docker registry
 - Installs wget to retrieve official MapGuide CentOS release tarballs
 - Installs key 32-bit libraries required by MapGuide to run within a 64-bit environment
 - Installs CentOS-flavored releases of FDO 3.9 and MapGuide Open Source 2.6
 - Installs supervisor to auto-start the bundled httpd and MapGuide Server daemon
 - Bundles the included supervisord.conf into the resulting image