[CHANGE] Add more basic technical Metadata to Files and Directories

[dla-kramski]

I would like to suggest identifying further basic technical metadata on files and directories, namely

• Owner
• Group
• Access permissions
• ACLs, if applicable.

Of course, you have to consider what occurs in all (or at least most) file systems.

Owners and groups probably only make sense in numerical form, and their mapping to readable names must be done externally.

It may make sense to create separate tables for certain file system types and fill them with their specific information.

[steffenfritz]

#110