Merge branch 'double-border-on-no-comments' into 'master'

border bottom for last comment fixes double line issue

Since image uploading isn't working atm. Will upload screenshots when it works again. 
https://unsee.cc/mosapine/
Fixes #3955 

See merge request !2175

app/assets/stylesheets/pages/note_form.scss

@@ -79,7 +79,6 @@
   padding: $gl-padding;
   margin-left: -$gl-padding;
   margin-right: -$gl-padding;
-  border-top: 1px solid $border-color;
   margin-bottom: -$gl-padding;
 }

app/assets/stylesheets/pages/notes.scss

@@ -128,7 +128,7 @@ ul.notes {
     }
     &:last-child {
-      border-bottom: none;
+      border-bottom: 1px solid $border-color;
     }
   }
 }