Prepare for Docker & Heroku

This is a preparation for Heroku or Docker PRs, that will require the app to be a 12 factor app.

Changelog

Added:

• Added viper dependency to load the env variables
• Added structured logging via logrus

Checklist

Ensure that before making this PR you have:

• Read the contributing guidelines
• Agreed with the LICENSE
• Run go fmt ./...
• Run go mod tidy