Renew the updater branch

Now with some actual consensus on what the updater will do!

mmc_updater/src/AppInfo.cpp

@@ -0,0 +1,23 @@
+#include "AppInfo.h"
+
+#include "FileUtils.h"
+#include "Platform.h"
+#include "StringUtils.h"
+#include "StandardDirs.h"
+
+#include <iostream>
+
+std::string AppInfo::logFilePath()
+{
+	return StandardDirs::appDataPath(organizationName(),appName())  + '/' + "update-log.txt";
+}
+
+std::string AppInfo::updateErrorMessage(const std::string& details)
+{
+	std::string result = "There was a problem installing the update:\n\n";
+	result += details;
+	result += "\n\nYou can try downloading and installing the latest version of "
+	          "MultiMC from http://multimc.org/";
+	return result;
+}
+