Add h* font size variables and margin

[whmii]

A proposition for consistent bottom margin across headers.
(this could be extended further to replace the multiple iterations $base-line-height / 2)

[kylefiedler]

@whmii when designing for apps I've never had consistent margin on the bottom of my headers. I felt like leaving it off caused less confusion for me when building out the rest of the site.

I like putting the h* sizes in variables though. I'm not crazy about those names though. I don't really like the way http://typeplate.com/ names them either.

[whmii]

Agreed, font-size variables can really help standardize things. I will modify the pr and repost…
Still having issues with the variable names if anyone has any sugestions

[tysongach]

@whmii @kylefiedler From a higher level, I think this raises an interested point: I believe we should state somewhere in the readme that Bitters is geared more towards creating apps, and not ‘marketing websites’. This isn’t to say that one can’t use Bitters for a regular marketing website, but with this clarification, the reasoning behind removing margins and other visual features would make more sense. Just a little sprinkle of purpose…

[kylefiedler]

@tysongach Agree, I created a issue to track that #70