Make early network accesses more reliable when using WLAN

The automatic update check is performed early during the application
start. It turns out that, when using a Wifi connection, the Qt
networking code is not ready yet at this point which leads to an
"Network inaccessible" error. This commit delays the automatic update
check until the network configuration is loaded completely.

See issue #1595.

src/RemoteDatabase.h

@@ -5,6 +5,7 @@
 #include <QtNetwork/QSslConfiguration>
 
 class QNetworkAccessManager;
+class QNetworkConfigurationManager;
 class QString;
 class QNetworkReply;
 class QSslError;
@@ -88,6 +89,7 @@ private:
     void clearAccessCache(const QString& clientCert);
 
     QNetworkAccessManager* m_manager;
+    QNetworkConfigurationManager* m_configurationManager;
     QProgressDialog* m_progress;
     QSslConfiguration m_sslConfiguration;
     QMap<QString, QSslCertificate> m_clientCertFiles;