重构弹出框等代码块位置，增加_Admin模板页中customModal块，支持子页面多个块

Bootstrap.Admin/Views/Admin/Users.cshtml

@@ -62,6 +62,6 @@
         </form>
     </div>
 }
-@section roleModal {
+@section customModal {
     @Html.Partial("RoleConfig")
 }

Bootstrap.Admin/Views/Shared/_Admin.cshtml

@@ -43,5 +43,4 @@
     </footer>
     <!--footer end-->
 </section>
-@RenderSection("modal", false)
-@RenderSection("roleModal", false)
+@RenderSection("modal", false)

Bootstrap.Admin/Views/Shared/_Default.cshtml

@@ -34,9 +34,7 @@
             </div>
         </div>
     </div>
-}
-@section roleModal {
-    @RenderSection("roleModal", false)
+    @RenderSection("customModal", false)
 }
 <div class="panel panel-default">
     <div class="panel-heading">查询条件</div>