private function loadInstallationMap()
	{
		if (file_exists($this->mapFile)) {
			if (!is_readable($this->mapFile) || is_dir($this->mapFile)) {
				throw new \Exception(sprintf(
					'Cannot read map file at %s', $this->mapFile
				));
			}

			$this->installationMap = json_decode(file_get_contents($this->mapFile), TRUE);

			if ($this->installationMap === NULL) {
				throw new \Exception(sprintf(
					'Broken map file at %s', $this->mapFile
				));
			}
		}
	}