build: reanimate the dead

Fix build with ndn-cxx 0.7.1 and ChronoSync 0.5.3

* Adapt to new API
* Upgrade to Qt5
* Several other bugs

Refs: #4563, #4087
Change-Id: Ic55d687caade08f557f9b9ec3e9569bc96798710
diff --git a/src/invitation.cpp b/src/invitation.cpp
index f311ad0..e7d2ac5 100644
--- a/src/invitation.cpp
+++ b/src/invitation.cpp
@@ -18,7 +18,7 @@
 
 using std::string;
 
-using ndn::IdentityCertificate;
+using ndn::security::Certificate;
 
 const size_t  Invitation::NAME_SIZE_MIN         = 7;
 const ssize_t Invitation::SIGNATURE             = -1;
@@ -51,7 +51,7 @@
 Invitation::Invitation(const Name& inviteeNameSpace,
                        const string& chatroom,
                        const Name& inviterRoutingPrefix,
-                       const IdentityCertificate& inviterCertificate)
+                       const Certificate& inviterCertificate)
   : m_inviteeNameSpace(inviteeNameSpace)
   , m_chatroom(chatroom)
   , m_inviterRoutingPrefix(inviterRoutingPrefix)