Updated delete_deployment and delete_role to support comp=media
so users can have Azure remove the underlying disks associated
with a deployment or a virtual machine. The main reason for this
change is commonly you'll run into a lease error if you remove
the virtual machine and then attempt to remove the vhd/blob.

This is treated as an optional parameter called delete_attached_disks

MSFT Docs:

http://msdn.microsoft.com/en-us/library/jj157184.aspx
http://msdn.microsoft.com/en-us/library/ee460815.aspx