fix issue silverapp#640 l10n localization of billing documents contex…

…t objects (eg. date)

silver/models/documents/base.py

@@ -33,7 +33,7 @@
 from django.db import transaction as db_transaction
 from django.db.models import Max, ForeignKey, F
 from django.template.loader import select_template
-from django.utils import timezone
+from django.utils import timezone, translation
 from django.utils.encoding import python_2_unicode_compatible, force_text
 from django.utils.text import slugify
 from django.utils.translation import ugettext_lazy as _
@@ -444,6 +444,9 @@ def get_template_context(self, state=None):
         if state is None:
             state = self.state
 
+        if settings.USE_I18N:
+            translation.activate(settings.LANGUAGE_CODE)
+
         return {
             'document': self,
             'provider': provider,