Codelist integration

* adds codelist app
* adds KonovaCodeList and KonovaCode model for fetching and storing OSIRIS Codelisten entries
* adds update_codelist command for updating and fetching codes
* adds autocomplete route for using codelists in forms

codelist/tests.py

@@ -0,0 +1,3 @@
+from django.test import TestCase
+
+# Create your tests here.