logging stuff

[softminus]

look at past logs to figure out what's logworthy

ideas

• unusual/unclassifiable error types
• unusual peer state transitions
• fast walker -> slow walker transition
• unusual states (no nodes to serve, no AllGood nodes, etc)

[softminus]

for more debug log; print out peerstats of interesting nodes (allgood / merelysyncedenough / etc)