This reverts commit e4308830.

- Set default hash to sha256.
- Rename domain variable to cn to be more understood.

- Mention need to copy the CA cert to clients.

- Forgot to explicitly set the RSA key size to be 2048 (defaulted to 512).

algorithm (according to the documentation) and OpenSSL ignores the field and
uses the default, which is MD5. Setting the default hash to SHA1.

- Found first bug (and fixed).

This reverts commit a85376bc.

- Merged the gen-ca command into the init command.
- Fixed a bug.
- Filled all commands (though not everything should be wokring yet).
- Keys and certificates have the subdomain name and the directory the domain.