Do not set OCIInsecureSkipTLSVerify based on registries.conf
Do not set OCIInsecureSkipTLSVerify based on registries.conf

- OCIInsecureSkipTLSVerify applies only to c/image/layout.Transport and
  c/image/archive.Transport; in both, ImageTransport.DockerReference
  always returns nil, which causes isReferenceSomething, and therefore
  isRegistryInsecure, to always return false; i.e., this code
  was never executed for those transports for which it could make a difference.

- The oci: and oci-archive: transports refer to local filesystems, so matching that
  against docker/distribution hostnames does not really make sense.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

Closes: #1255
Approved by: rhatdan

TomSweeneyRedHat/buildah,rhatdan/buildah,ipbabble/buildah,TomSweeneyRedHat/buildah,projectatomic/buildah,nalind/buildah-1,projectatomic/buildah,nalind/buildah-1,nalind/buildah,projectatomic/buildah,rhatdan/buildah,TomSweeneyRedHat/buildah,rhatdan/buildah,ipbabble/buildah,nalind/buildah,nalind/buildah-1