Setup CI/CD in order to deploy with stages

[comoser]

• CI/CD can be whatever, as long as it works
• Create CI/CD process with staging and production
• Staging and production builds will be based on tags in the main branch
• Environment variables need to be set accordingly to the env
• We will use semver to keep track of rc <-> staging and final <-> production
• The API is currently deployed in Heroku, with all the free tiers
• We should setup the provisioning of the environment from heroku programatically (app.json and setting it up with addons for DB)