fix development mode, which was not working before, and add instructions on how to build the Docker container for both development and production mode (the latter is the default);
fix error handling in development mode, to bring it up to modern usage with Express 4;
bake the portal files into the docker image, instead of mounting a volume (mounting a volume with the node_modules folder was causing a problem);
add http -> https redirection in production mode (fixes #107).
This PR will:
node_modulesfolder was causing a problem);