Consider allowing only attachment of full device (sda, not sda1) in the manager menu

[joanna]

If we attach a specific partition, e.g. sda1, then it won't appear in the VM's filemanager. So, perhaps a good tradeoff between usability and flexibility would be to only present a list of full devices in the manager menu, so to guarantee that the volume(s) appear automatically in the VM's manager. On the other hand, an advanced user willing to attach only a specific partition, could always use qvm-block command line to do that.

[marmarek]

​http://git.qubes-os.org/gitweb/?p=marmarek/qubes-manager.git;a=commit;h=b650a3a27678a3be0bc8ca6fc79c72f7333516d1

Still allow to detach partition if attached manually.
Partition detection heuristic is quite dumb, but should work in most cases (detect sda2 naming scheme, but not d0p1 and not partitions >= 10).