Add qsf export function.

Migrated from: https://tracker.clearos.com/view.php?id=1947

Reported by: Dave Loper

Add QSF export function to backup app and marketplace app. This would exist as a library and would also need to be parsed by the configuration backup utility. Would store the parsed file as HOSTNAME.installed_apps.qsf in /var/clearos/configuration_backup/

May need to add a backup of repositories used on a system as well so that if contribs or other repos are invoked throughout the lifecycle of the product would be able to be restored.