added variables && adjusted headings to react to variables

added line-height helper class

added documentation to line-height

fixed line-height mixin

added line-height mixin to headings

replaced all font-size: 16 with base font size variable

imported variables into text-margin

changed name from line-height to m-line-height

using base-font size & base-line-height from the settings file now.
hotfixed npm version badge
switch gemnasium for david dm in readme
Added hyphens, ligatures | closes #54

added hyphens

added openType ligatures

added boolean on/off switch for ligatures in settings.styl

added hyphens mixin to mixins.styl

added font-size-adjust:auto for firefox