Allow http stuff to be none (for importation)

access_landing/models.py

@@ -26,13 +26,17 @@ class Institute(models.Model):
     internal_host = models.CharField(
         max_length=1000,
         verbose_name=_("internal host"),
-        help_text=_("host which the proxy should point to (with protocol)")
+        help_text=_("host which the proxy should point to (with protocol)"),
+        null=True,
+        blank=True
     )
 
     external_host = models.CharField(
         max_length=1000,
         verbose_name=_("external host"),
-        help_text=_("proxy fqdn (without protocol)")
+        help_text=_("proxy fqdn (without protocol)"),
+        null=True,
+        blank=True
     )
 
     active = models.BooleanField(default=True, verbose_name=_("active"))