Merge remote-tracking branch 'origin/v3' into v3

# Conflicts:
#	client/noop.go
#	errors/errors_test.go
#	logger/unwrap/unwrap_test.go
#	register/memory/memory_test.go
#	server/noop_test.go
#	service.go
#	util/dns/cache.go
#	util/dns/conn.go
#	util/structfs/metadata_ec2.go
#	util/time/duration.go

util/jitter/ticker.go

@@ -16,7 +16,6 @@ type Ticker struct {
 	C    chan time.Time
 	min  int64
 	max  int64
-	exp  int64
 	exit bool
 	rng  rand.Rand
 }