Add weathermap

[marcelb98]

It would be nice if we would show a network weathermap (map of our switches and routers, maybe aggregated to buildings, with the current amount of traffic flowing between them) of our network on our website.
The general idea would be:

• use a SVG with tags on the lines which represent the connections as the underlying image of our network (we already maintain such a graphic, but haven't added those tags to the lines)
• have a list which assigns those tags to checks in our monitoring
• add a new endpoint to sipa which fetches all the needed link information from our monitoring and returns them as JSON
• add the SVG to our webpage and fill in the values from the JSON with some Javascript

I've tagged this issue as an easy task, since it is a nice first project for new active members, as you don't need deep knowledge of our infrastructure to do it but you'll definitely learn some things about our infrastructure.