Take care of the display only in the ShelfMonitor

Summary

In the current implementation, data retrieval is not fully separated from the data display. For example, the CSS classes are set in C++ while the values are processed. Ideally, the AMCMonitor wouldn't care about the display at all, but just export the monitorable values.

The Javascript code (in the ShelfMonitor) should retrieve the label.json file and use it to display the data accordingly. More generally, the ShelfMonitor class should not be much more than a Javascript web interface.

What is the expected correct behavior?

Data visualization is completely separate from the monitoring core.