InitDepot creates the depot directory, which stores key/csr/crt files.

NewCertRequestCommand sets up a "request-cert" command to create a request for a new certificate (CSR).

NewInitCommand sets up an "init" command to initialize a new CA.

NewRevokeCommand revokes the given certificate by adding it to the CA's CRL.

NewSignCommand sets up a "sign" command to sign a CSR with a given CA for a new certificate.