Added: VerifiableModel from Coadjutor
Added: VerifiableModel from Coadjutor

Coadjutor had a helper called `VerifiableModel`. This was completely dependent
on `HumanError`.  Since we're using absolutely nothing else in `coadjutor`, I'm
moving this from there, into `human_error`.

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Branch:        refactor/stop-monkeypatching-activerecord-objects
Change-Id:     I0a8bd55d93a2adb3d1e2a41c30f631e353d9b006
Signed-off-by: Jeff Felchner <8a84c204e2d4c387d61d20f7892a2bbbf0bc8ae8@thekompanee.com>

jasnow/human_error,jasnow/human_error