Adds https redirection in production mode

[augusto-herrmann]

This PR will:

• 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 SSL sign up issues #107).