Now that Alertmanager provides status=(unprocessed|suppressed|active) in the API it doesn't make sense to keep having separate filters for each value, merge @silenced & @inhibited into a single filter, update docs and UI
This moves raven init into a dedicated file where it's configured on load, we no longer load it on /help, but there's only css there so there wasn't anything that could fail anyway. We will also now fail in the most visible way if the value passed to raven is invalid (as in invalid syntax)
