I followed the readme and not sure the directions are up to date.
I did Dependencies

cd $GOPATH/src/github.com/microservices-demo/payment/
go get -u github.com/FiloSottile/gvt
gvt restore

I'm not a go developer but does not this just get the gvt src thus need to craete the gvt executable and install it? i.e. gvt is not found for me.

Next not sure the next directions are correct either WRT cd $GOPATH/src/github.com/microservices-demo/payment/paymentsvc/
I cloned the repo to my local machine and no such paymentsvc directory exists at that level but in a sub directory of cmd i.e. $GOPATH/github.com/microservices-demo/payment/cmd/paymentsvc