api: use django DATETIME_FORMAT to format dates

Also add a custom DATETIME_FORMAT value to French locale, without seconds.

chrono/api/views.py

@@ -15,8 +15,8 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from django.db.models import F
+from django.utils.formats import date_format
 from django.utils.timezone import localtime
-from django.utils.translation import ugettext as _
 
 from rest_framework import serializers, status
 from rest_framework.generics import GenericAPIView
@@ -29,7 +29,7 @@ class Datetimes(GenericAPIView):
     def get(self, request, pk=None, format=None):
         response = {'data': [{
                         'id': x.id,
-                        'text': localtime(x.start_datetime).strftime(_('%Y-%m-%d %H:%M'))}
+                        'text': date_format(localtime(x.start_datetime), format='DATETIME_FORMAT')}
                              for x in Event.objects.filter(agenda=pk).filter(
                                      places__gt=F('booked_places'))
                              ]}

chrono/formats/fr/formats.py

@@ -0,0 +1 @@
+DATETIME_FORMAT = 'j F Y H:i'

chrono/settings.py

@@ -105,6 +105,8 @@ USE_TZ = True
 
 LOCALE_PATHS = (os.path.join(BASE_DIR, 'chrono', 'locale'), )
 
+FORMAT_MODULE_PATH = 'chrono.formats'
+
 # Static files (CSS, JavaScript, Images)
 # https://docs.djangoproject.com/en/1.7/howto/static-files/