Read list of authors from a text file, filtering comments.

def get_authors():
    """Read list of authors from a text file, filtering comments."""
    authors = []
    authorfile = os.path.join('doc', 'authors.txt')
    with codecs.open(authorfile, 'r', 'utf-8') as f:
        for line in f:
            line = line.strip()
            if line and not line.startswith(u'#'):
                authors.append(line)
    return u", ".join(authors)