Add uniq index on name+args

[searls]

We want to make sure that name, args, and result have a unique constraint.

• If we try to insert and this is violated, then select that row and compare the results:
  • If the results match, it's just an extraneous record, so do nothing
  • if the results do not match, then raise, print the recorded & new result value and explain the mismatch and suggest the user figure it out (e.g. write a comparator or delete the old record with Suture.delete from Verify: API to delete a row from calls #10)