Recomend using String#dump when embedding user-input into output/exceptions/log messages

```
Simply embedding a variable into a String, which is then printed or written to 
a log file may result in forged messages. Instead, String#dump should be called.

puts "Received message: #{mesg.dump}"

log.info "User logged in: #{username.dump}"

raise("invalid command: #{command.dump}")
```

Original issue reported on code.google.com by `postmode...@gmail.com` on 21 Sep 2012 at 1:25
