logic: Added update checker connecting to online API

* connects to https://www.sourcetrail.com/api/v1/versions/latest
* sends information about OS, platform, license type, current version and a unique user token
* Automatic update check is enabled via Startscreen and performed once every 24 hours on window focus
* Update check can be forced by clicking on "check for new version" on start screen
* renamed TimePoint to TimeStamp

fortune cookie message = In Träumen und im Leben ist nichts unmöglich.

src/lib_gui/qt/network/QtRequest.cpp

@@ -0,0 +1,40 @@
+#include "qt/network/QtRequest.h"
+
+#include <QNetworkAccessManager>
+#include <QNetworkReply>
+
+#include "utility/logging/logging.h"
+
+QtRequest::QtRequest()
+{
+	m_networkManager = new QNetworkAccessManager(this);
+	QObject::connect(m_networkManager, SIGNAL(finished(QNetworkReply*)), this, SLOT(finished(QNetworkReply*)));
+}
+
+void QtRequest::sendRequest(QString url)
+{
+	LOG_INFO_STREAM(<< "send HTTP request: " << url.toStdString());
+
+	QNetworkRequest request;
+	request.setSslConfiguration(QSslConfiguration::defaultConfiguration());
+	request.setUrl(QUrl(url));
+	m_networkManager->get(request);
+}
+
+void QtRequest::finished(QNetworkReply *reply)
+{
+	QVariant statusCodeV = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);
+	QVariant redirectionTargetUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
+
+	if (reply->error() != QNetworkReply::NoError)
+	{
+		LOG_ERROR_STREAM(<< "An error occured during http request. ERRORCODE: " << reply->error());
+	}
+
+	QByteArray bytes = reply->readAll();
+	LOG_INFO_STREAM(<< "received HTTP reply: " << bytes.toStdString());
+
+	delete reply;
+
+	emit receivedData(bytes);
+}