Rename/move command

[larryfenn]

We'd like to change the s3 path on demand. This is chiefly being raised now as an issue because it would be an important component of an overarching 'project rename' utility.

• Prompt for a new bucket name

• The data should be moved in s3 from the old bucket to the new bucket in a hopefully stable way (i.e. if something catastrophic happens to cancel it, it doesn't break all the data)

• The config file should change to point to the new bucket

• The old bucket should be deleted