[Twisted-web] Use nevow:pattern and nevow:attr to render a list of

[Jean-Paul Calderone]

Your code loads the pattern and then drops it on the floor.  Beyond that, your
render method returns None, meaning the tag with the render directive is removed
from the output and replaced with the "big red None" you see.

When you create a pattern, you have to put it somewhere in order for it to
matter.  This means returning it from a render method, adding it as a child
to a tag in the output, or filling a slot with it.

And when you write a render method, it needs to return something.  Whatever it
returns will be used in place of the tag which had the render directive.

Jean-Paul