Merge branch 'font-variable' into 'master'

Removes the hard-coded font in the diff notes

Removes the hard-coded font in the diff notes and switches to using the $regular_font variable.

See merge request !259

app/assets/stylesheets/sections/notes.scss

@@ -81,7 +81,7 @@ ul.notes {
 .diff-file .notes_holder {
   font-size: 13px;
   line-height: 18px;
-  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
+  font-family: $regular_font;
 
   td {
     border: 1px solid #ddd;