Fix invalid syntax

Hi,

in the current version 0.9.1 I got the following error:
```
    [11:58:24] % python repository/manage.py version_control postgres://postgres:pw@example.com/db proj
      File "repository/manage.py", line 5
        main(debug='False', six='<module 'six' from '/usr/lib/python2.7/dist-packages/six.pyc'>')
                                         ^
        SyntaxError: invalid syntax
```

The reason was, that the manage.py looked like this:

```
    #!/usr/bin/env python
    from migrate.versioning.shell import main
    if __name__ == '__main__':
        main(debug='False', six='<module 'six' from '/usr/lib/python2.7/dist-packages/six.pyc'>')
```