fix broken doctests.

I don't like to receive emails about broken builds every day so I fixed this one.

```
File "/var/lib/jenkins/jobs/ftw.blog-mle-sl-blog-test-plone-4.2.x.cfg/workspace/ftw/blog/tests/blog.txt", line 27, in blog.txt
Failed example:
    portlet_manager['content_type']['Blog'].keys()
Differences (ndiff with -expected +actual):
    - [u'blog-categories', u'tagcloud', u'blog-archive']
    ?  -                   -            -
    + ['blog-categories', 'tagcloud', 'blog-archive']
----------------------------------------------------------------------
File "/var/lib/jenkins/jobs/ftw.blog-mle-sl-blog-test-plone-4.2.x.cfg/workspace/ftw/blog/tests/blog.txt", line 29, in blog.txt
Failed example:
    portlet_manager['content_type']['BlogEntry'].keys()
Differences (ndiff with -expected +actual):
    - [u'blog-categories', u'tagcloud', u'blog-archive']
    ?  -                   -            -
    + ['blog-categories', 'tagcloud', 'blog-archive']
----------------------------------------------------------------------
File "/var/lib/jenkins/jobs/ftw.blog-mle-sl-blog-test-plone-4.2.x.cfg/workspace/ftw/blog/tests/blog.txt", line 31, in blog.txt
Failed example:
    portlet_manager['content_type']['BlogCategory'].keys()
Differences (ndiff with -expected +actual):
    - [u'blog-categories', u'tagcloud', u'blog-archive']
    ?  -                   -            -
    + ['blog-categories', 'tagcloud', 'blog-archive']
```