Remove the "done" message displayed at the end of the compilation with Rhino.

Hi.

The "done" message, displayed at the end of the compilation, is useless, in my opinion.

Moreover, in the context of a web application that computes the stylesheet when it is necessary (through [lesscss-java](https://github.com/marceloverdijk/lesscss-java), for instance), the done message is stored in the log of the application, meanwhile no bug has happened. I personally try to only display bugs and warning in the logs, in order to not pollute them.

That is why I suggest to remove this message.

What do you think?

Thanks,
Guillaume