add a `--all` flag to delete command to remove all transactions at once

[andynog]

Currently there is no way to remove / delete all transactions in a particular path all at once. If you use the delete command you have to specify the index if there are more than 1 transaction in a particular path.

In order to allow users to remove all the transactions in a path add the flag --all to the delete command and remove all the transactions at once.

It would be good to also have a confirmation message asking the user for confirmation on executing this command since it removes several transactions at once.