docker: btcd requires Go 1.8 or newer and fails to build with 1.7
docker: btcd requires Go 1.8 or newer and fails to build with 1.7

The btcd docker container fails to build with Golang 1.7 because this
version of go is missing time.Until (used by the btcd server)

LightningNetwork/lnd,aakselrod/lnd,LightningNetwork/lnd,aakselrod/lnd