def save(file)
      File.open(file, "w") do |f|
        f.write(@raw_cert.to_pem)
      end
      true
    end
def save(file)
      File.open(file, "w") do |f|
        f.write(@raw_cert.to_pem)
      end
      true
    end
Save certificate to file in PEM format

 === Parameters
 file(String):: File path name

 === Return
 true:: Always return true