contactmodel: keep repsence state after subscription

Change-Id: I3501d0ba072bc68685af8ba8c46c22979cc25493

src/libclient/contactmodel.cpp

@@ -930,6 +930,7 @@ ContactModelPimpl::addToContacts(const QString& contactUri,
     if (iter != contacts.end()) {
         auto info = iter.value();
         contactInfo.registeredName = info.registeredName;
+        contactInfo.isPresent = info.isPresent;
         iter.value() = contactInfo;
     } else
         contacts.insert(iter, contactInfo.profileInfo.uri, contactInfo);