Add conversion fns to deal with file modes.

Also add stubs for ctime/mtime/size
Flesh out build-manifest.

Also add a fn for flattening a tree represented as a nested map
Add CSV and time dependencies
Add an ns to handle CSV manifests created by the Python version of tardis
Add time and size info to file backup metadata
Fix typos that called s3 fns rather than just accessing the var
Start adding restore functionality