Only show the message if user is not the owner

Closes #323

app/views/projects/pages/_destroy.haml

-- if can?(current_user, :remove_pages, @project) && @project.pages_deployed?
-  .panel.panel-default.panel.panel-danger
-    .panel-heading Remove pages
-    .errors-holder
-    .panel-body
-      %p
-        Removing the pages will prevent from exposing them to outside world.
-      .form-actions
-        = link_to 'Remove pages', namespace_project_pages_path(@project.namespace, @project), data: { confirm: 'Are you sure?'}, method: :delete, class: "btn btn-remove"
+- if can?(current_user, :remove_pages, @project)
+  - if @project.pages_deployed?
+    .panel.panel-default.panel.panel-danger
+      .panel-heading Remove pages
+      .errors-holder
+      .panel-body
+        %p
+          Removing the pages will prevent from exposing them to outside world.
+        .form-actions
+          = link_to 'Remove pages', namespace_project_pages_path(@project.namespace, @project), data: { confirm: 'Are you sure?'}, method: :delete, class: "btn btn-remove"
 - else
   .nothing-here-block Only the project owner can remove pages