Put ENABLE_GOOGLE_AUTH setting back

Fixes:
* #267
* #345 
* #349 
If `session.get(session['user'])` returns `None` then the first time line 45 runs you're pretty certain to get an `AttributeError` raised:

```
>>> getattr(None, 'picture')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'picture'
>>> 
```

@marcua's suggestion to use `getattr(user, key, None)` will avoid the `AttributeError` and could fix #349 if it's okay with whatever code uses `user_dict` for it to have `None` values.

I'm not sure but it looks like none of these attributes are actually used in the current templates.

Note also #355 which seems like it is probably also caused by this loop (but under different circumstances).