Implement CoreOS/etcd based seamless seed servers.
Don't terminate if etcd offline; sleep and retry.
Rewrite the scanner algorithm into a seeder impl.
Add probing seed generator and distribution tests.
Fix some minor goofs.
Rewrite bootstrapper, rate limiting still needed!
Fix copy paste typo.
Only skip local addr:port, other ports allow.
Reduce bootsrap probing rate (bug in pastry).