Fix upgrade and downgrade regarding disk.dev_type
Fix upgrade and downgrade regarding disk.dev_type

The up/downgrade procedure so far did not consider the
changes in the 'dev_type' attribute of disks. This patch
adds relevant checks and updates. A related problem
was that the logical IDs of disks were adjusted depending
on the dev_type, which made the order of updates not
arbitrary anymore. To make this more robust, the upgrade
procedure also considers the old versions of dev_types
(at least for 2.9).

Signed-off-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>
Reviewed-by: Thomas Thrainer <98bdeac947eb8ca18146e9ce7f092788ec242cd1@google.com>

mbakke/ganeti,ganeti/ganeti,leshchevds/ganeti,bitemyapp/ganeti,onponomarev/ganeti,leshchevds/ganeti,leshchevds/ganeti,bitemyapp/ganeti,andir/ganeti,ganeti/ganeti,mbakke/ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/ganeti,grnet/snf-ganeti,apyrgio/ganeti,mbakke/ganeti,andir/ganeti,onponomarev/ganeti,apyrgio/snf-ganeti,yiannist/ganeti,dimara/ganeti,dimara/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,ganeti/ganeti,yiannist/ganeti