Allow for either druid:file or druid:container mapping in manifest.csv

[blalbrit]

In the current accessioning paradigm, we have two models:

• objects that have only one file
• objects that have many files

For case one, users have become accustomed to having a flat directory for the content, and then mapping the file to the druid in the manifest.csv ( | druid | filename | ).

For case two, users have become accustomed to having sub-directories for each object ( | druid | folder | ).

In our current implementation of the pre-assembly app, it is expected that all content (whether one-file-per-object or many-files-per-object) will be arranged in object-level sub-directories ( | druid | object | ).

This is a placeholder ticket to address whether or not we can add back in the functionality to map to either a single file or to a container in a future iteration of this app.