Deleting empty folders after archiving data.

[bazkiaei]

In its current state, the data archiving process moves data to a target location and leaves the empty folders that used to contain the data. This results in a great number of empty folders that we have to delete by hand.

While deleting empty folders might be risky, it is worth adding some methods to delete the empty folders to classes responsible for archiving data. We should make using these methods optional with a default setting of not using them until we discuss this more in detail and make a decision on how to delete empty folders.