Django:如何正确地设置和更改反映url的语言?

settings.py:
INSTALLED_APPS = [
    ...,
    'modeltranslation',
]
TIME_ZONE = 'Europe/Belgrade'
USE_I18N = True
USE_L10N = True
USE_TZ = True
LANGUAGES = (
    ('en-us', _('English')),
    ('hu', _('Hungarian')),
    ('sr-latn', _('Serbian')),
)
LOCALE_PATHS = (
    os.path.join(BASE_DIR, 'locale'),
    os.path.join(BASE_DIR, 'books', 'locale'),
)

urls.py:
urlpatterns = [
    url(r'^i18n/', include('django.conf.urls.i18n')),
    ]
urlpatterns += i18n_patterns(
    url(_r('^books/'), include('books.urls', namespace='books'))
    )
settings.py:
INSTALLED_APPS = [
    ...,
    'm