Nested belongs_to

Here you go, mostly the problems were because of your stuff, like the double-link to lender/user via Item and Loan.  Also see I had to remove the `anaf` in Item.

I had to comment out the image validation, it was just throwing errors, even with an image in there.

Then for `build_item` I had to merge in the `user: lender` to get that to validate (that's the double-linking issue), and because I needed `lender` I had to do something in the controller a bit different to ensure that.