Allow swiftmetrics-dash to be deployed on a subrouter

[tobespc]

Right now, swiftmetrics-dash will appear as an endpoint to the router passed in as app:8080/swiftmetrics-dash

We need to enhance this so that we can have it deployed with subrouting i.e.

app:8080/something/something/swiftmetrics-dash

Currently, if put the dashboard on a subrouter with that path the dashboard is accessible under that path, but the internal parts that it uses are not loaded under that path they are loaded without that path prefixed

@vincent-coetzee Raised this on slack