add checkpoints for 0.8.0 release (#550)
add checkpoints for 0.8.0 release (#550)


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