Fix problems with models which have a "model" field
this is probably an issue in more places than just this
 As a workaround you could try using the db_column attribute on your field named "model":

``` python

class MyModel(Model):
    model_alias = CharField(db_column='model')
```
 So far my project works fine with the change in the pull request (without workaround). Should I look for more places in the code with this problem and submit another pull request, or is there another plan?
 I apologize for taking a while getting to this, I'll see about merging something up in the next day or two.

The same solution is already being used by the Q class.
