Gc\Core\Updater\Adapter\Basic::upgrade PHP Method

    public function upgrade()
    {
        $backupFilename = $this->getTmpPath() . '/backup.zip';
        //Remove old backup
        if (file_exists($backupFilename)) {
            unlink($backupFilename);
        }
        if (File::isWritable(GC_APPLICATION_PATH, array(GC_APPLICATION_PATH . '/data/cache', GC_APPLICATION_PATH . '/.git'))) {
            if ($this->createBackup($backupFilename)) {
                foreach (array('library', 'module', 'vendor', 'tests') as $directory) {
                    $this->addMessage(sprintf('Remove %s directory', GC_APPLICATION_PATH . '/' . $directory));
                    File::removeDirectory(GC_APPLICATION_PATH . '/' . $directory);
                }
                $directory = $this->getTmpPath() . '/v' . $this->getLatestVersion();
                $this->addMessage(sprintf('Copy %s to %s', $directory, GC_APPLICATION_PATH));
                File::copyDirectory($directory, GC_APPLICATION_PATH);
                $this->addMessage('Done!');
                return true;
            }
        }
        $this->addMessage('Some files are not writable!');
        $this->addMessage(sprintf('Please execute: chmod -R ug+rw %s', GC_APPLICATION_PATH));
        return false;
    }