Usage of jekyll-postcss-v2

[pedrogxv]

Hello, I used this boilerplate to create some type of portfolio for myself using jekyll and it helped me a lot, thanks.

Locally I has some problems using in windows with postcss, I fixed with jekyll-postcss-v2 which seems to me a "upgraded" version of jekyll-postcss in used by this boilerplate, so I was thinking if it is a good idea to use it here instead of the current 'v1' of postcss, what do you think?

I can make this change and propose a PR if it seems to be appropriate.