The Nodejs backend

[smackthat]

Build a backend for the app by using Nodejs and Express. Should serve as a proxy to the Trefle API, so the API secret token is kept secret. Also, in production mode serves the client side build.

Functionalities:

• Should handle request that gets all the plants for a selected region from the API.
• Should handle a request that gets single plant's info.
• Should get distribution zones for selected plant.
• Should serve the client build in production.