Make request handler sorting persist

[Citymonstret]

When the server shuts down, a file will be written containing the order of request handlers (using CSV). On startup these will be read, and the request handlers will be ordered accordingly. The counts will still be set to zero, as to not prevent the requests from being sorted in real-time according to the current requests.

Possibly also reset the counters after every sort. This way the head will always the the currently most requested handler.