Include a `--style=sass` or `--style=css` while initialising an app.

[zerefwayne]

While doing create-react-app <app-name> to initialise an app, I want to include a flag:

create-react-app <app-name> --style=sass : It will pre-include sass preprocessors and make scss files in the directory out of the box.

@ianschmitz @iansu I feel this is an important feature which is present in angular-cli but not in create-react-app.

[mrmckeb]

Hi @zerefwayne, we're actually looking at templates right now... which should solve this issue - see #6270.

Let me know if you think this won't be suffice.