Snipcart less theme

There is still some work to do to make it a lib.
Extract our own styles and only keep colors, fonts and tweaks to snipcart.

I disabled minifying for easier debugging. Forgot to enable it back...
My initial tought was to use https://www.npmjs.com/package/gulp-autoprefixer
But looks like the package is broken at the moment.
We could definitly use http://lesshat.madebysource.com/ also (i prefer autoprefixer though...)
Thoughts ?