1. This moves blackout period to `shutdown: blackout_seconds:`
1. This moves a blackout period logic to `LifecycleEvents`
1. This makes `web_exporter` to use lifecycle events
   for blackout period
1. This adds additional health check to look at state
   of master process
1. Exempt `/liveness` and `/readiness` from Rack Attack
1. Make `/liveness` and `/readiness` to not hit DB/Redis
1. Optimise Rack Attack handling