bump default connection limit to 30

I can get 29 weaves running on my laptop, and once all connections are
established, the avg cpu load is ~10%. 30 runs into difficulty because
the concurrent connection establishment does create a very high load,
resulting in some timeouts. But that wouldn't happen when running each
weave in a separate machine (with more CPU resources overall than my
single laptop).

Stop gap solution for #426.

weaver/main.go

@@ -56,7 +56,7 @@ func main() {
 	flag.IntVar(&wait, "wait", 0, "number of seconds to wait for interface to be created and come up (defaults to 0, i.e. don't wait)")
 	flag.BoolVar(&debug, "debug", false, "enable debug logging")
 	flag.StringVar(&prof, "profile", "", "enable profiling and write profiles to given path")
-	flag.IntVar(&connLimit, "connlimit", 10, "connection limit (defaults to 10, set to 0 for unlimited)")
+	flag.IntVar(&connLimit, "connlimit", 30, "connection limit (defaults to 30, set to 0 for unlimited)")
 	flag.IntVar(&bufSz, "bufsz", 8, "capture buffer size in MB (defaults to 8MB)")
 	flag.Parse()
 	peers = flag.Args()