remove walletinfo fields related to stakemining purchaser (#612)
remove walletinfo fields related to stakemining purchaser (#612)


jrick/btcd,jcmincke/dcrd,jcmincke/dcrd,jcmincke/dcrd,decred/dcrd,decred/dcrd,jrick/dcrd,jrick/dcrd,jrick/btcd,jrick/btcd