motivation: address feedback from community, prepare for moving api to official repo
changes:
* add reset method to counter
* do not force the user facing metric object to implement the mteric handler protocol. this was done for convinience and confuses matters
* adjust tests
* fix a few typos
motivation: after much discussion around logging API, we settled on a different API style, primairly the fact that we will use initializers instead of factories
changes:
* introduce intermediate classes for Counter, Timer and Recorder which are designed to replace the Metrics.makeCounter, Metrics.makeTimer and Metrics.makeRecorder APIs and wrap corresponding CounterHandler, TimerHandler and ReorderHandler coming from the metrics implmentation
* rename Metrics to MetricsSystem
* rename MetricsHandler -> MetricsFactory
* remove Metrics.withCounter, Metrics.withTimer and Metrics.withRecorder syntactic sugar
* rename Metrics.timed with Timer.measure
* make sure metrics system can only be initialized/bootstrapped once per process
* adjust and add tests
* add a bit of docs on key APIs