Reduce redundant requests

[Dave Shoreman]

If there are a handful of AJAX requests pending and one of them comes back with a 401 Unauthenticated response, there's little sense in continuing. This is probably most likely to happen when refreshing the page after the session expires.

Need to figure out how axios deals with cancelling a request so that we can hook into certain fail cases and abort any requests that're still outstanding. If a request comes back unauthorised, we should probably just redirect to the login page which would at least prevent any further calls to get system stats.