Add utf-8 support in slugs with autoslug

Slugs end up empty if list name consists only of non-ascii characters
and that results in an error. Autoslug converts non-ascii characters to
appropriate ascii ones and auto-updates the slug when list name changes.

Add unidecode dependency and fix PEP8 errors

models.py: add one blank line for PEP8

setup.py

@@ -99,6 +99,7 @@ setup(
     include_package_data=True,
     zip_safe=False,
     tests_require=['tox'],
+    install_requires=['django-autoslug', 'unidecode', ],
     cmdclass={
         'clean': Clean,
         'test': Tox,

todo/models.py

@@ -3,24 +3,18 @@ import datetime
 
 from django.db import models
 from django.contrib.auth.models import Group
-from django.template.defaultfilters import slugify
 from django.core.urlresolvers import reverse
 from django.utils.encoding import python_2_unicode_compatible
 from django.conf import settings
+from autoslug import AutoSlugField
 
 
 @python_2_unicode_compatible
 class List(models.Model):
     name = models.CharField(max_length=60)
-    slug = models.SlugField(max_length=60, editable=False)
+    slug = AutoSlugField(populate_from='name', editable=False, always_update=True)
     group = models.ForeignKey(Group)
 
-    def save(self, *args, **kwargs):
-        if not self.id:
-            self.slug = slugify(self.name)
-
-        super(List, self).save(*args, **kwargs)
-
     def __str__(self):
         return self.name