Compare synchronized files by checksum

[tom114]

Describe your idea for a new feature

When files are synchronized between IRIDA installations, a checksum (md5, sha, etc.) should be run to verify the files were correctly transferred.

Describe how you would access this feature?

Users wouldn't see this feature. It would be used in the sync service to verify files sync'd properly and mark as error if they didn't.

Additional information

This is an offshoot of #175