914923d125f5d17b39b4dc05f666d130e80a68b2 Add setting as known type (Peter Bushnell)

Pull request description:

When loading old wallets I get "Unknown wallet records" showing up in the log file. The key that is adding to the unknown record count is "setting", this is a known key removed in the 0.6 release of Bitcoin in the commit linked below. The "setting" key is not known to the wallet anymore, like "acentry" which is not added as an unknown record, but the "setting" key was used in previous versions of Bitcoin.

ninja check check-functional