Add to examples of storm logging

[daluu]

Not that it's critical, but would be helpful to users if you added an example of storm logging for the bolt example.

e.g. for the BasicBolt example: self.log("a message",self);

I had to look into lib/storm.js and do trial & error runs to confirm the above call syntax was to be used. Would have been simpler if an example showcased its use.