Refactor host user security model, support static assets in modules and themes, module definition permissions and categories, paging control, remove SiteUsers, move seed data from script to site template for installation

Oqtane.Client/Modules/Admin/Pages/Add.razor

@@ -37,7 +37,7 @@
         </td>
         <td>
             <select class="form-control" @onchange="(e => ParentChanged(e))">
-                <option value="">&lt;Site Root&gt;</option>
+                <option value="-1">&lt;Site Root&gt;</option>
                 @foreach (Page page in pages)
                 {
                     <option value="@(page.PageId)">@(new string('-', page.Level * 2))@(page.Name)</option>
@@ -191,7 +191,7 @@
         try
         {
             parentid = (string)e.Value;
-            if (string.IsNullOrEmpty(parentid))
+            if (parentid == "-1")
             {
                 children = PageState.Pages.Where(item => item.ParentId == null).ToList();
             }