postcss integration

[bkinsey808]

If you are interested, I would love to see postcss (for processing css files) in this project. There are a lot of very interesting postcss plugins available nowadays, it would be great to have the power and flexibility of tapping into these. Some of the plugins that intrigue me are:

• for future syntax css: http://cssnext.io/
• for flexbox in older browsers: https://github.com/10up/flexibility (https://github.com/7rulnik/postcss-flexibility)

[alexpods]

@bkinsey808 Sorry for delay with answer, I was kinda busy these days. Of course postcss is must-have today. It's support was implemented in #44. I've added only one plugin by default: postcss-cssnext. I don't think many people need flexibility plugin. After all it's quite simple to add its support:

1. npm install -D postcss-flexibility
2. Add require('postcss-flexibility') here

[alexpods]

One more thing: don't use the starter until #43 is resolved. Huge refactoring is coming..