Render correct layout, css fix empty state of ldap links

Fixes #157

app/controllers/groups/ldap_group_links_controller.rb

@@ -2,6 +2,8 @@ class Groups::LdapGroupLinksController < ApplicationController
   before_action :group
   before_action :authorize_admin_group!
+  layout 'group'
+
   def index
   end

app/views/ldap_group_links/_ldap_group_links.html.haml

@@ -8,4 +8,5 @@
     %ul.well-list
       = render collection: group.ldap_group_links, partial: 'ldap_group_links/ldap_group_link', locals: { group: group }
   - else
-    %p No linked LDAP groups
+    .panel-body
+      No linked LDAP groups