Add zip options

[egrace479]

The first version of this script actually looked at the contents of a zip folder and ran checksums. It would be great to have a zip option to get the checksums of the contents of a zip file.

[thompsonmj]

For storing the output of ZIP content checksums alongside those of the rest of the target directory contents, would the following example output CSV structure make sense?

filepath,filename,md5
target_dir/docs/file1.txt,file1.txt,<checksum>
target_dir/data/archive.zip,archive.zip,<checksum>
target_dir/data/archive.zip/image1.jpg,image1.jpg,<checksum>

[egrace479]

I like the idea that we treat a zip file like both a file and folder, in that it gets its own checksum and the contents get checksums (following rules established in the function call). For instance, we can then see that the structure of the zip has changed without having to compare filepaths even if all the files themselves remain unchanged.