client: add bulk delete feature (#459)

This introduces a new privilege 'posts:bulk-edit:delete' which by default is given to power users.

client/html/posts_header.tpl

@@ -28,4 +28,11 @@
             %><a href class='mousetrap button append close'>Stop editing safety</a><%
         %></form><%
     %><% } %><%
+    %><% if (ctx.canBulkDelete) { %><%
+        %><form class='horizontal bulk-edit bulk-edit-delete'><%
+            %><a href class='mousetrap button append open'>Mass delete</a><%
+            %><input class='mousetrap start' type='submit' value='Delete selected posts'/><%
+            %><a href class='mousetrap button append close'>Stop deleting</a><%
+        %></form><%
+    %><% } %><%
 %></div>

client/html/posts_page.tpl

@@ -50,6 +50,10 @@
                                 <% } %>
                             </span>
                         <% } %>
+                        <% if (ctx.canBulkDelete && ctx.parameters && ctx.parameters.delete) { %>
+                            <a href class='delete-flipper'>
+                            </a>
+                        <% } %>
                     </span>
                 </li>
             <% } %>