Add station health/data quality indicators to Stations page

[153957]

It would be useful to be able to see the health (based on to be determined parameters) of each station on the stations page.

• Has it uploaded data yesterday
• What was the quality of that data
  • Shift in MPV value
  • Change in total number of events
  • ..
• Recent problems
• ..

[davidfokkema]

Part of that was the focus of my local sparklines branch. I'll look into this.

[davidfokkema]

And, of course, Wytse and Sjoerd are looking into a meaningful definition of 'health'.

[153957]

This can also be integrated into Nagios, so Nagios can warn our contacts that their station needs to be looked at.

[153957]

The added Pulseheight MPV indicators should be merged into one 'Data quality indicator', with options to add extra checks, such as baseline, n_peaks, pulseintegral mpv, etc..