Improve metrics

When investigating/monitoring the performance of the app and servers, the metrics are very important, but I think some improvements can be made here:

- Autorefresh of the charts, so you don't have to click on the Metrics page manually every x minutes to see the latest metrics. Especially when looking at some of the bottom charts, you'd first have to scroll all the way to the top before you can load the Metrics page again.

- Charts per minute for days older than 24H. Now, the 'Day' chart shows detailed information on the last 24H, but sometimes you want to look back at the charts in detail of days older than 24H. This is currently not possible. You'd have to look at the Week or Month charts for this, but this information is averaged out, so is often misleading and inaccurate.

- Finer granularity: sometimes, information per minute is not enough and I'd want to see it per second.