Is this correct? I can't seem to get this to work on master.

```
$> python
>>> import IPython
>>> IPython.__version__
'2.0.0-dev'
>>> 
$> ipython --version
2.0.0-dev
```


```
$> ipython nbconvert 05_NumpyIntro.ipynb --to slides --slide-notes=True
...
[NbConvertApp] CRITICAL | Bad config encountered during initialization:
[NbConvertApp] CRITICAL | Invalid argument: '--slide-notes=True'
```

If I'm doing something dense then I'd be more than happy to take this to the mailing list.

Thanks!