Put some space between paragraphs in comments, to make them more easily distinguishable.

Since this is styling, it works retroactively on all existing comments, too!

public/stylesheets/sass/application.sass

@@ -622,7 +622,10 @@ ul.show_comments,
       :margin
         :bottom 0
         :top 0
-    .ltr 
+    p + p
+      :margin
+        :top 1em
+    .ltr
       ol, ul
         padding-left: 2em
         li