Archiving/deleting API calls - new implementation

[iskitsas]

We need to implement a new API call, in order for old revisions to delete the physical asset on the disk to save some space.

The CMS by default never deletes any physical asset on the disk. But this can lead to situations where the disk is full and there is no really a need to keep all these files for old revisions.

It would by nice to be able to mark old revisions as "archived" and having the physical asset on the disk truly deleted. We will keep all the revision history, but not the physical asset on the disk.