Enable configuration of PORT and SSL_PORT

[rahearn]

For our use-case, we need to be able to listen on port 8080 instead of 9000. This change enables that while leaving default behavior almost completely unchanged.

• Existing use cases of docker run -p 9000:9000... will continue to work unchanged
• Anyone using docker run -P to automatically map container ports to random host ports will need to add --expose=9000 --expose=9443 to their command to maintain the same behavior.

If we were running entirely in docker, we could have done this with -p 8080:9000 but our environment actually unpacks the docker image and repacks it in another buildpack, so we can't use the -p flag and instead have to rely on $PORT

[rahearn]

Converting this to draft as I work out some issues with this implementation with our provider.