Add function to list yes/no values for rating.

This is to get two lists inside the template that we can render beautifully.

schulfrei_servicerating/models.py

@@ -51,6 +51,17 @@ class ServiceRating(models.Model):
     rating_other_selfhosting = models.BooleanField(_('Self-hosting possible'),
         help_text=_('The service can be hosted locally without limitations.'))
 
+    def yes_no_dict(self):
+        yes = []
+        no = []
+
+        for field in self._meta.fields:
+            if field.name.startswith('rating_'):
+                (yes if getattr(self, field.name) else no).append(
+                    (field.verbose_name, field.help_text))
+
+        return (yes, no)
+
     @property
     def rating_privacy(self):
         return 0.34 * (1 if self.rating_privacy_transfer else 6) + \