Look for fixity files that don't match exact name

[jimtuttle]

The DLP Ingest: Fixity File Specification specifies that the name of the file may be individualized to the collection:

The file must be named "checksums-md5.txt" or checksums-md5-.txt so we look for checksums-*.txt to allow for more specific information useful to the depositor.

This app should look for checksums-md5-*.txt.