Fix #236 : django 1.8 deprecation messages during server start

Signed-off-by: CapsLock <faimaison@legeox.net>

coin/offers/forms.py

@@ -9,5 +9,6 @@ class OfferAdminForm(ModelForm):
     class Meta:
         model = Offer
         widgets = {
-            'configuration_type' : Select(choices=(('','---------'),)+Configuration.get_configurations_choices_list())
-        }
+            'configuration_type': Select(choices=(('','---------'),) + Configuration.get_configurations_choices_list())
+        }
+        exclude = ('', )

requirements.txt

@@ -7,7 +7,7 @@ django-autocomplete-light==2.0.0a18
 reportlab==2.5
 django-activelink==0.4
 html2text
-django-polymorphic==0.5.6
+django-polymorphic==0.6
 django-sendfile==0.3.6
 -e git+https://code.ffdn.org/zorun/django-postgresql-netfields.git#egg=django-netfields
 -e git+https://github.com/chrisglass/xhtml2pdf@a5d37ffd0ccb0603bdf668198de0f21766816104#egg=xhtml2pdf-master