* main:
Simplify domain language to just "boot" and unscoped config keys
Retain a fixed number of containers when pruning
Don't assume rolling back in message
Check all hosts before rolling back
Ensure Traefik service name is consistent
Extend traefik delay by 1 second
Include traefik access logs
Check if we are still getting a 404
Also dump load balancer logs
Dump traefik logs when app not booted
Fix missing for apt-get
Report on container health after failure
Fix the integration test healthcheck
Allow percentage-based rolling deployments
Move `group_limit` & `group_wait` under `boot`
Limit rolling deployment to boot operation
Allow performing boot & start operations in groups