Document and fix development, staging and production configuration

[rngadam]

• In development, we want to be able to point to the local environment
• Staging is to http://dev.scry.info/
• Production will be something else

Right now, this is set in scry-frontend/src/Components/Remote.js:

const dev = false;

export const API = dev ? 'http://localhost:1234' : 'https://dev.scry.info/scry2';

export const Publisher = dev ? 'http://localhost:2222' : 'https://dev.scry.info:443/meta';

not suitable. should be picking up from a .json file (perhaps served from public) and be selectable in frontend.