Set a GOPATH in Makefile to prevent gom erroring.
Set a GOPATH in Makefile to prevent gom erroring.

If the GOPATH is unset, this leads to an error:

  go: GOPATH entry is relative; must be absolute path: "".

Setting a GOPATH avoids this (it's not actually used becuase gom adds
its own path to the GOPATH, but this prevents the error)

alphagov/router