Update backup script to create curation log entry and filesystem flag

[rija]

User story

As a curator
I want the dataset files I'm publishing to Wasabi to be also backed up to S3 Glacier
So that I have piece of mind that any dataset files we publish has a backup available

Acceptance criteria

Given a dataset being curated has files associated with it
When I call the command to backup the dataset files
Then a prominent flag file "backup.in.progress" is written to the user dropbox being backed up

Given a dataset being curated has files associated with it
When I call the command to backup the dataset files
And the backup has completed successfully
Then the prominent flag file "backup.in.progress" is removed

Given a dataset being curated has files associated with it
When I call the command to backup the dataset files
And the backup has completed successfully
Then a new entry is add to the Curation log announcing success of backup process

Given a dataset being curated has files associated with it
When I call the command to backup the dataset files
And the backup has failed
Then a new entry is add to the Curation log announcing failure of backup process