Set DateTimePickerInput.format on Django 1.7+

Conflicts:
	oscar/forms/widgets.py

oscar/forms/widgets.py

@@ -1,14 +1,16 @@
-from django.core.files.uploadedfile import InMemoryUploadedFile
 import re
 import six
 from six.moves import filter
 from six.moves import map
 
+import django
 from django import forms
+from django.core.files.uploadedfile import InMemoryUploadedFile
 from django.forms.util import flatatt
 from django.forms.widgets import FileInput
 from django.template import Context
 from django.template.loader import render_to_string
+from django.utils import formats
 from django.utils.encoding import force_text
 from django.utils.html import format_html
 from django.utils.safestring import mark_safe
@@ -128,7 +130,11 @@ class DateTimePickerInput(forms.DateTimeInput):
         include_seconds = kwargs.pop('include_seconds', False)
         super(DateTimePickerInput, self).__init__(*args, **kwargs)
 
-        if not include_seconds:
+        # Django 1.7+ has format default as 0
+        if django.VERSION >= (1, 7):
+            self.format = self.format or formats.get_format(self.format_key)[0]
+
+        if self.format and not include_seconds:
             self.format = re.sub(':?%S', '', self.format)
         add_js_formats(self)