* Rework Scope metrics according to Prometheus conventions.
- counters should end with _total
- elaborated and added units to help strings
- recommended for cache hit/miss metrics: track only the total and the
hits and in separate metrics, since the most common query will be
"hits / total"
- track all times in seconds (base units), which has become the standard
recommendation
- other small changes
There could be more changes that would require more thinking (what
dimensions to use, summaries vs. histograms, etc.), but this is probably
enough controversial material already :)
* Use timeRequestStatus() in sqs_control_router.go.
