This is a complementary fix for #1105 (Create Linux VM Wizard: use scsi
as default bus/device) and add some logic to the list of controllers
presented in the ControllerSelector combo box
Since we can have IDE, SCSI, Virtio(blk) as a controller during installation,
based on OS detection and personal preferences, we can reasonably assume
on 80 % of cases it will be the same controller we want to use for the
next time we add a hardisk.
This allows backward compatibility for Linux guests which were proposed a
virtio-blk as first choice, and also helps newly created Linux VMs by proposing
SCSI.
this is ExtJS recommended practise, follows most of our
conventions and is necessary for querying
components with Ext.ComponentQuery.query() without escaping the
dots in the component widget name.
