Jambonz medium

[eravelo]

This PR introduces a third AWS deployment configuration called jambonz-medium . The goal is to limit the number of instances involved while making the version upgrades easier by sharing the database. Changes from the jambonz-mini deployment include:

• use autoscaling group
• use a shared RDS instance in place of the local mysql server
• use a shared Elasticache instance in place of the local redis server
• add an HTTPS Load Balancer in front of the WebServer, Homer and Grafana (which uses a SSL certificate managed by ACM)
• temporary disable fail2ban to avoid Load Balancer's failing healthcheks (should be improved)
• jambonz-monitoring server runs in its own instance (built from jambonz-scalabale-production)

[eravelo]

I'm closing this PR in favor of https://github.com/jambonz/jambonz-infrastructure/pull/61