pelican_import fix for bs4

Quick fix for this traceback:
$ pelican-import --wpfile ~/Downloads/mysite.wordpress.2013-02-24.xml 
Traceback (most recent call last):
  File "/Users/me/.virtualenvs/pelican/bin/pelican-import", line 8, in <module>
    load_entry_point('pelican==3.2', 'console_scripts', 'pelican-import')()
  File "/Users/me/.virtualenvs/pelican/src/pelican/pelican/tools/pelican_import.py", line 363, in main
    disable_slugs=args.disable_slugs or False)
  File "/Users/me/.virtualenvs/pelican/src/pelican/pelican/tools/pelican_import.py", line 238, in fields2pelican
    for title, content, filename, date, author, categories, tags, in_markup in fields:
  File "/Users/me/.virtualenvs/pelican/src/pelican/pelican/tools/pelican_import.py", line 37, in wp2fields
    if item.fetch('wp:status')[0].contents[0] == "publish":
TypeError: 'NoneType' object is not callable

I'm a BeautifulSoup novice but these changes allowed me to import two of my wordpress.xml files.