add the resource's GOPATH to global GOPATH
add the resource's GOPATH to global GOPATH

Signed-off-by: Sebastian Sangervasi <4368c9a8cc4025fbaa35e5d7e2c7b7b7d9b28fd1@gmail.com>

ggeorgiev/docker-image-resource,concourse/docker-image-resource,SillyMoo/docker-image-resource,ggeorgiev/docker-image-resource,concourse/docker-image-resource,barthy1/docker-image-resource,SillyMoo/docker-image-resource,barthy1/docker-image-resource