z3c.rml fails to bootstrap itself

The bootstrap.py was too old, resulting in this error:

```
Traceback (most recent call last):
  File "bootstrap.py", line 108, in <module>
    pkg_resources.Requirement.parse('distribute')).location
AttributeError: 'NoneType' object has no attribute 'location'
```

This pull request fixing that by upgrading to the latest bootstrap. In
addition the version pin for Pillow is updated. This was necessary since
the previous version no longer installs on many systems.