CSS only version

[moebiusmania]

following #27 we are going to introduce a first iteration of a "CSS only" version of Habitat in v1.0, to provide basic library usage and UI/UX consistency in regular HTML environments, especially landing pages buit with 3rd party tools.

• habitat tokens usable as CSS classes
• typography elements usable as CSS classes
• habitat components usable as CSS classes
• provide examples on Storybook
• update documentation

some parts will be dependants on #50

[moebiusmania]

I'm going to update the related branch and create a draft PR to better explain the situation @pietrograndi