`POST /configs/origin` does not normalize the hostname

[zomglings]

If you add a new origin https://<host>/ and then look up https://<host> (no trailing slash) on /configs/is_origin, you get the response:

{"origin":null,"updated_at":null,"created_at":null}

We should normalize all new origins when they are added to the API to remove trailing slashes.

[kompotkot]

Also we need to allow duplication of resources. And make is_origin authentificated.