Added PCKS12 command line option

Modified parsing of CLI to allow either specifying ca/cert/key files or single pkcs12 file.

PKCS12 support

Embed PKCS12 certificate chain.

.ovpn file generator and importer

• Use Cobra for commands
• import existing OpenVPN config and embed the certificate/key files
• generate simple OpenVPN config file with the provided certificate/key file names,