title: Return QuerySet from a RawQuerySet
body: <p>I am trying to create a queryset from a rawqueryset, but the changelist is always saying <code>Something's wrong with your database installation. Make sure the appropriate database tables have been created, and make sure the database is readable by the appropriate user.</code><br><br>
  This is my attempt (is a simple query, but it will became more complex and I need a raw SQL query):<br></p>
  
  <pre><code>class MyModelAdmin(admin.ModelAdmin):
      def queryset(self, request):
          qs = MyModel.objects.raw('SELECT field1, field2 FROM MyTable)
          return qs
  </code></pre>
  
  <p>Is there any way to show this raw query in my changelist view applying <code>admin.site.register(MyModel, MyModelAdmin)</code> in admin.py?</p>