fixing implicit @site argument causing errors on inherited controllers

I found that some routes have no explicit `@page` object to define `:page_id` argument, when inherited controller uses a route with no :site_id, expecting to use the default/current site. With this scenario, the following error occurs:

```
ActionView::Template::Error (No route matches {:action=>"index", :controller=>"comfy/admin/cms/pages"} missing required keys: [:site_id]):
    37: = form.form_group :class => 'form-actions' do
    38:   = form.submit t('.preview'), :name => 'preview', :id => nil, :class => 'btn btn-default'
    39:   = form.submit t(@page.new_record?? '.create' : '.update'), :class => 'btn btn-primary'
    40:   = link_to t('.cancel'), comfy_admin_cms_site_pages_path, :class => 'btn btn-link'
  app/controllers/comfy/admin/cms/pages_controller.rb:22:in `new'
  app/controllers/admin/content/pages_controller.rb:3:in `new'
```

```
class Admin::Content::PagesController < Comfy::Admin::Cms::PagesController
  def new
    super
  end
end
```

I also fixed similar occurrences in other views.