fix(text): allow theming font family (#720)

Author: montezume

src/components/typography/text/text.styles.js

@@ -8,7 +8,7 @@ const getBaseStyles = (props, theme) => {
   };
 
   return `
-   font-family: ${vars.fontFamilyDefault};
+   font-family: ${overwrittenVars.fontFamilyDefault};
    color: ${overwrittenVars.colorSolid};
 `;
 };