Tweak Makefile test configuration

[Integralist]

NOTE: The following error is why I removed the -i flag from make test.

➜  make test
go test -i $(go list ./... |grep -v 'vendor') || exit 1
go test: -i flag is deprecated
go test runtime/cgo: copying /Users/integralist/Library/Caches/go-build/7e/7eb8ae2d3970b1de52ae6d42d0a04a014fdad25c2f0026bce5d9ec33c67d5527-d: open /usr/local/go/pkg/darwin_amd64/runtime/cgo.a: permission denied
make: *** [test] Error 1

[smaeda-ks]

LGTM, thank you!