Investigate using rsync --delete vs md5sum to verify transfers

[tjk584]

Rsync has built in deletion with rsync --delete after transferring a file. Rsync also using checksums to verify that transfers are successful.

Replacing our current transfer verification method with rsync --delete may make our data flow faster and more efficient.

[tjk584]

rsync --delete removes files from the destination - this isn't what we want to do.

If anything, we should use rsync --remove-source-files, which removes files once they have been successfully transferred.