WL-2463 Don't load properties from DB for provided.

When loading provided users by AID don't load any properties from the DB as there won't be any and we can't create any through the API.
WL-2463 Don't lookup or cache properties when ID is null.

When loading a user from the provider and we don't' have an ID yet we can end up caching the resource properties against an ID of null which can end up being retrieved in a different lookup.
Merge pull request #4 from ox-it/WL-2463

WL-2463 Fix for ending up with wrong unit details.