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/apps.py

@@ -0,0 +1,5 @@
+from django.apps import AppConfig
+
+
+class CodelistConfig(AppConfig):
+    name = 'codelist'