backup & restore qrexec policy

[rootkovska]

Allow to backup and restore qrexec policy. Restore from designated mgmt VMs (i.e. not just from dom0).

[rootkovska]

BTW, I assume this will also imply proper backup and restore qubes' tags...

[DemiMarie]

There needs to be a way of stating, “Qube X is allowed to manipulate policies of qubes with tag Y, but not of any other qubes.”