Merge branch 'clipboard-button' into 'master'

Remove white background on clipboard button; position icon

## What does this MR do?
Removes white background from clipboard button

## What are the relevant issue numbers?
Closes #19098 

## Screenshots (if relevant)
![Screen_Shot_2016-07-18_at_3.12.24_PM](/uploads/4a6a540e1a074e6cf89fb99be1b49f2d/Screen_Shot_2016-07-18_at_3.12.24_PM.png)
![Screen_Shot_2016-07-18_at_8.50.55_PM](/uploads/8c594b6f9a74095b194fe1f634eaf226/Screen_Shot_2016-07-18_at_8.50.55_PM.png)

See merge request !5335

app/assets/stylesheets/framework/sidebar.scss

@@ -198,6 +198,10 @@ header.header-pinned-nav {
 
   .sidebar-collapsed-icon {
     cursor: pointer;
+
+    .btn {
+      background-color: $gray-light;
+    }
   }
 }
 

app/assets/stylesheets/pages/issuable.scss

@@ -122,7 +122,8 @@
 
     button {
       float: right;
-      padding: 3px 5px;
+      padding: 1px 5px;
+      background-color: $gray-light;
     }
   }