Resolved TypeError stemming from dependency on old yeoman-generator version

On one machine, this generator worked beautifully. On the other it did not: I got a TypeError stemming from trying to show colors on the cute little initialization menu. It turns out that is because on the non-working machine I had up-to-date yeoman packages. After some research it turns out this was a bit of an issue for generator-webapp, among others, because yeoman changed how it would display stuff in the terminal.

Anyway, the changes are minimal but now this works for me.