* swarm/shed: remove metrics fields from DB struct
* swarm/schunk: add String methods to modes
* swarm/storage/localstore: add metrics and traces
* swarm/chunk: unknown modes without spaces in String methods
* swarm/storage/localstore: remove bin number from pull subscription metrics
* swarm/storage/localstore: add resetting time metrics and code improvements
* swarm/shed: add metrics to each shed db
* swarm/shed: push metrics prefix up
* swarm/shed: rename prefix to metricsPrefix
* swarm/shed: unexport Meter, remove Mutex for quit channel
