shares: NamespacePaddingShare can take advantage of Go's memory guarantees to zero memory and use make([]byte, LEN) instead of bytes.Repeat([]byte{0}, LEN) which is less efficient

shares: NamespacePaddingShare can take advantage of Go's memory guarantees to zero memory and use make([]byte, LEN) instead of bytes.Repeat([]byte{0}, LEN) which is less efficient #17