Added legacy model definition back for seamless backwards compatibility.

Updated readme.
Added sample legacy model implementation.

adminsortable/__init__.py

@@ -1,4 +1,4 @@
-VERSION = (1, 8, 5)  # following PEP 386
+VERSION = (2, 0, 0)  # following PEP 386
 DEV_N = None
 
 

adminsortable/models.py

@@ -124,8 +124,12 @@ class SortableMixin(models.Model):
             extra_filters, filter_on_sortable_fk)
 
 
-# for easier legacy support of existing implementations
+# for legacy support of existing implementations
 class Sortable(SortableMixin):
 
     class Meta:
         abstract = True
+        ordering = ['order']
+
+    order = models.PositiveIntegerField(default=0, editable=False,
+        db_index=True)