Use Yeoman log to output usage end message instead of using Console object

This PR is trivial. It removes use of Console from source code and uses built-in Yeoman log to output messages:
https://github.com/yeoman/generator/blob/master/lib/base.js#L124-L126
The reasoning for this is to cleanup code and use single method across project's source code to output messages
The second commit is purely cosmetic, but I think can help to avoid future problems when wording is to be changed in end messages.

If you want commits to be rebased, just let me know.