query_method ignores default property values when creating the query filters

When an entity is created by `endpoints-proto-datastore` from the ProtoRPC message, if a property isn't provided in the request it uses the default value. This actually doesn't make sense for `query_method` requests as it creates a scenario where the query filter will use the default value of properties. A quick example might help explain the issue clearer:

```python
class MyModel(EndpointsModel):
    name = ndb.StringProperty()
    deleted = ndb.BooleanProperty(default=False)

@MyModel.query_method(path='', http_method='GET', name='list',
                      query_fields=('limit', 'order', 'pageToken'),
                      collection_fields=['id',]+MyModel._properties.keys())
    def model_list(self, query):
        return query
```

`MyModel` has several entities:
  `MyModel(name='Person A', deleted=False)`
  `MyModel(name='Person B', deleted=True)`

In the above `query_method` request, I expect to get both entities back. 

What actually happens is only `Person A` is returned. The reason for this is because when the deleted property is not provided, it is set to `False` and thus the resulting `Query` that is created by `endpoints-proto-datastore` has a filter with `MyModel.deleted == False`.