Add compatibility for YAML in Ruby 1.8

For Bad Reasons (tm), Ruby 1.8's YAML parser expects a lot more spaces
than Ruby 1.9's does. Let's humor it and give it those spaces.

bind/einhorn.go

@@ -70,7 +70,7 @@ func einhornBind(n int) (net.Listener, error) {
 }
 
 // Fun story: this is actually YAML, not JSON.
-const ackMsg = `{"command":"worker:ack","pid":%d}` + "\n"
+const ackMsg = `{"command": "worker:ack", "pid": %d}` + "\n"
 
 func einhornAck() {
 	if !usingEinhorn() {