Upgrade to Django 1.11

- Deprecation warnings using Django 1.8 are resolved.
- Deprecation warnings using Django 1.11 are resolved.

- Admin: grappelli is no longer used.
- Upgrade to django-autocomplete-light v3 (v2 is not 1.11 compatible).
  * autocomplete.modelform_factory being dropped, code uses dal Select2
    views and widgets.

utils/views/autocomplete.py

@@ -0,0 +1,26 @@
+from django.db.models import Q
+
+from dal import autocomplete
+
+
+class Select2QuerySetView(autocomplete.Select2QuerySetView):
+    model = None
+    search_fields = []
+
+    def get_queryset_filter(self):
+        q = self.q
+        filter_q = Q()
+
+        if not q:
+            return filter_q
+
+        words = q.split()
+
+        for word in words:
+            for field in self.search_fields:
+                filter_q |= Q(**{'{}__icontains'.format(field): word})
+
+        return filter_q
+
+    def get_queryset(self):
+        return self.model.objects.filter(self.get_queryset_filter())