Add "Check for updates" Feature

This patch adds a check for updates feature.

It connects to http://subsurface.hohndel.org/updatecheck.html to check for
any new versions. It then prompts the user with a download link if an
update is available.

Signed-off-by: Joseph W. Joshua <joejoshw@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/updatemanager.h

@@ -0,0 +1,21 @@
+#ifndef UPDATEMANAGER_H
+#define UPDATEMANAGER_H
+
+#include <QObject>
+
+class QNetworkAccessManager;
+class QNetworkReply;
+
+class UpdateManager : public QObject
+{
+	Q_OBJECT
+public:
+	explicit UpdateManager(QObject *parent = 0);
+	void checkForUpdates();
+private:
+	QNetworkAccessManager *manager;
+public slots:
+	void requestReceived(QNetworkReply* reply);
+};
+
+#endif // UPDATEMANAGER_H