This commit changes the way walletBirthday is stored in the synchronizer and intinitializer. Wallets syncing from creation/restore would have a problem where the birthday stored in the Blocks Table would be the one corresponding to the chekpoint found a the time of syncing, but the compact block downloader would start downloading blocks from the height provided by the user when the wallet was restored. This would cause a `validationFailed` error at the height checkpoint.height + 1 and restart downloading from checkpoint.height and then resume correctly.
Darksidewalletd test setUp was changed re be able to reproduce the error since injection guaranteed correctness and it was not possible to reproduce the error with it since the wallet birthday height provided matched exactly with the checkpoint on disk and that's the only case that avoided this error.
Closes#444
3be694c920