attrdict causing issues with doctests
Using the suggested method of `from peewee import *` brings in `JOIN` and friends, which are all instances of `attrdict`.

If you want to write and run doctests in your code, then, running `python -m doctest your_script.py` will throw a `KeyError` as it attempts to look up the `__wrapped__` attribute as `doctest` checks to see if it's a wrapped function. Example follows:

```python
File "C:\Users\Kenne\.virtualenvs\nicecore\lib\site-packages\peewee.py", line 318, in __getattr__
  return self[attr]
KeyError: '__wrapped__'
```

Seems like the solution would be to add a `try/except` block to the `attrdict` class.