Improved the way we display the executed isntaller command

This PR tries to solve #80 for the most used case.  Around 80% of users use Linux or Mac and most of them will install the installer in `/usr/local/bin/`, so we can easily improve commands' output.
Of course :(  I'm really ashamed of my self for not having used `PATH_SEPARATOR` constant from the very beginning. Hopefully this is fixed for real now.