feat(http): add prometheus counters for tracking write/query usage
feat(http/metric): add metric recoder for recording http metrics
feat(prometheus): implement metric.Recorder for prometheus metrics
fix(prometheus): remove erroneous fmt.Printlns
feat(http): add prometheus registry to API backend
This was done as exposing prometheus metrics to a higher level was quite
difficult. It was much simple to simply pass the registry down to
anything that needs it.
feat(cmd/influxd/launcher): pass prom registry in on api backend
feat(http): collect metrics for write and query endpoints
This was much messier than I would have preferred. Future work is
outlined in TODOs.
review(influxdb): rename metric.Metric to metric.Event
Michael Desa