em.skin makes assumptions about content 

E.g. here it expects that a `blog` object exists:

```
    folder = portal['blog']
  File "/home/john/zope/plumi/buildout-cache/eggs/Zope2-2.13.15-py2.7.egg/OFS/ObjectManager.py", line 777, in __getitem__
    raise KeyError, key
KeyError: 'blog'
```

This could be dealt with in the `plumisite` buildout part to create the initial site, or maybe better upon installation of `em.skin`
