Improve launcher management of files

There are multiple cases for which it would be useful to get some file management from the launcher:

• templates deployment (which files were previously deployed with another selected template?)
• marketplace packages management at distribution upgrade
• being able to identify locally modified files (versus those coming from the distribution, the templates or the marketplace packages)
• Debian upgrades
• remove obsolete files at upgrade
• MP with template deploying a file to nxserver/config, the file needs to be removed when uninstalling the MP (example: Social Collaboration MP)

For those tasks, we would need:

• some files listings
• optionally, md5 sums
• obsolete files removal