Syntactic sugar classes for ancestor queries

[dragonx]

Just a small replacement Manager class that lets you specify ancestor queries more easily, ie:

MyModel.objects.ancestor(ancestor_key).filter(property="blah")

All you have to do is replace the model "objects" object:

from djangoappengine.db.models.Manager import Manager

class MyModel(models.Model):
    objects = Manager()
    id = DbKeyField(primary_key=True, parent_key_name='parent_key')
    property = models.IntegerField()