merge r1538 from branches/ganeti/ganeti-1.2
merge r1538 from branches/ganeti/ganeti-1.2

Check HVM device type on instance modify as well.

Reviewed-by: imsnah



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