Bad log formatting in workers.go

[karalabe]

Just saw this in my IPFS logs:

16:07:31.315 DEBUG    bitswap: %!s(int=1)  keys in bitswap wantlist workers.go:188

Apparently you are using log.Debug(n, " keys in bitswap wantlist") to print this message (which btw is valid according to the interface), it's however not implemented correctly by go-logger, which uses %s as the format string for all parameters.

My initial idea was that this should be fixed in the logger, but changing it from %s to %v might have cascading adverse effects on the entire IPFS codebase, so maybe it's better to roll with the fault and maybe document the issue?

cc @whyrusleeping