Remove Block Button from Abuse Reports page if User is Already Blocked

An addition to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2292

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/4667

See merge request !2313

app/views/admin/abuse_reports/_abuse_report.html.haml

@@ -23,6 +23,9 @@
         data: { confirm: "USER #{user.name} WILL BE REMOVED! Are you sure?" }, remote: true, method: :delete, class: "btn btn-xs btn-remove js-remove-tr"
 
   %td
-    - if user
+    - if user && !user.blocked?
       = link_to 'Block user', block_admin_user_path(user), data: {confirm: 'USER WILL BE BLOCKED! Are you sure?'}, method: :put, class: "btn btn-xs"
+    - else
+      .btn.btn-xs
+        Already Blocked
     = link_to 'Remove report', [:admin, abuse_report], remote: true, method: :delete, class: "btn btn-xs btn-close js-remove-tr"