Remove go test -i ./...; not needed with go 1.10
Remove go test -i ./...; not needed with go 1.10

go 1.10 now caches properly, so -i shouldn't be needed anymore.

Refs:
- https://golang.org/doc/go1.10#build
- https://golang.org/cmd/go/#hdr-Build_and_test_caching

maruel/gohci,maruel/gohci,periph/gohci,periph/gohci