add shell of tests page, lighten form actions background and give it a variable

docs/templates/pages/css-tests.mustache

@@ -0,0 +1,6 @@
+<!-- Masthead
+================================================== -->
+<header class="jumbotron subhead" id="overview">
+  <h1>{{_i}}Tests{{/i}}</h1>
+  <p class="lead">{{_i}}{{/i}}</p>
+</header>

docs/templates/pages/less.mustache

@@ -378,6 +378,10 @@
             <td><code>@inputDisabledBackground</code></td>
             <td><code>@grayLighter</code></td>
           </tr>
+          <tr>
+            <td><code>@formActionsBackground</code></td>
+            <td><code>#f5f5f5</code></td>
+          </tr>
         </tbody>
       </table>
       <h4>{{_i}}Form states and alerts{{/i}}</h4>