Stop using navigation properties in UserStore

- Will follow up in a different PR with fixup/loading of navigation properties (they are not populated correctly today)
- Also adds some tests that load from the database (confirming that navigation properties aren't loaded today)

cc @suhasj @divega 
I'm not sure, but today the navigation properties aren't properly loaded at all (since we weren't Including them), so I just commented out all references to them until we either fix them, or remove them