Certificate revocation

Adds the handling of certificate revocation according to ndncert protocol v0.2.
Includes handing on CA module, client module as well as the test cases for these funcationalities.

Currently no internal database are being updated from the revocation.
This actual update and propagation of revocation information needs to relies on a certificate log, which can be attached to the CA module using status update callback.

Change-Id: I21f912285161ce781e17d222e640c8f0c57b50f7
diff --git a/src/certificate-request.cpp b/src/certificate-request.cpp
index 3798ea6..4a4c4b4 100644
--- a/src/certificate-request.cpp
+++ b/src/certificate-request.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2017-2019, Regents of the University of California.
+ * Copyright (c) 2017-2020, Regents of the University of California.
  *
  * This file is part of ndncert, a certificate management system based on NDN.
  *
@@ -26,21 +26,23 @@
 
 CertificateRequest::CertificateRequest() = default;
 
-CertificateRequest::CertificateRequest(const Name& caName, const std::string& requestId, int status,
+CertificateRequest::CertificateRequest(const Name& caName, const std::string& requestId, int requestType, int status,
                                        const security::v2::Certificate& cert)
   : m_caPrefix(caName)
   , m_requestId(requestId)
+  , m_requestType(requestType)
   , m_status(status)
   , m_cert(cert)
 {
 }
 
-CertificateRequest::CertificateRequest(const Name& caName, const std::string& requestId, int status,
+CertificateRequest::CertificateRequest(const Name& caName, const std::string& requestId, int requestType, int status,
                                        const std::string& challengeStatus, const std::string& challengeType,
                                        const std::string& challengeTp, int remainingTime, int remainingTries,
                                        const JsonSection& challengeSecrets, const security::v2::Certificate& cert)
   : m_caPrefix(caName)
   , m_requestId(requestId)
+  , m_requestType(requestType)
   , m_status(status)
   , m_cert(cert)
   , m_challengeStatus(challengeStatus)