fix(cmd): Move user interaction from Stdout to Stderr

It avoids polluting stdout.
refactor(cmd/export): add --insecure option

It exports decrypted key when set --insecure.
fix(pkix/csr): record IP address in CommonName

Set it as 'IP Address' in 'Subject Alternative Name' of certificate when signing.
style(cmd): rewrite error message
Merge pull request #10 from unihorn/33

refactor(cmd/export): add --insecure option