Add finished signal to Resource loading

libraries/networking/src/ResourceCache.cpp

@@ -380,6 +380,7 @@ void Resource::finishedLoading(bool success) {
         _failedToLoad = true;
     }
     _loadPriorities.clear();
+    emit finished(success);
 }
 
 void Resource::reinsert() {

libraries/networking/src/ResourceCache.h

@@ -201,6 +201,9 @@ signals:
     /// This can be used instead of downloadFinished to access data before it is processed.
     void loaded(const QByteArray& request);
 
+    /// Fired when the resource has finished loading.
+    void finished(bool success);
+
     /// Fired when the resource failed to load.
     void failed(QNetworkReply::NetworkError error);