Remove out-of-date typography CSS classes

Author: rstoenescu

src/css/core/typography.styl

@@ -87,11 +87,6 @@ sub
 sup
   top -.5em
 
-.strong
-  font-weight bold
-.emphasize
-  font-style italic
-
 blockquote
   padding: $spaces.small.y $spaces.regular.x
   margin 0