Fabio Hernandez reports that he really would like the return of the feature that allowed file lists to be specified from a text file. I think that we should probably do this by supporting standard input. Something like:

$ cat myfiles.txt | butler ingest-raws myrepo

rather than adding a --file option explicitly. This seems more unix-y. The text file can contain anything that would be valid for the "LOCATIONS" parameters: so directories, files, or URIs. We probably shouldn't worry about trying to expand wildcards (which would normally be done by the shell).