For Multiple database setup

[WAS33M]

This is a fix for the Django admin sortable 2 plugin to work with multiple database setting. after this update, user can set db_tablespace parameter in model meta data to use a different database than the default database.

class Meta: db_tablespace = "*****"

In order to reproduce this update/bug simply use multiple databases in project settings and attach the sortable model with database other than the default database. Plugin will still try to perform query on default database resulting in table does not exist error exception.