KVM: replace unsupported arguments during migration
KVM: replace unsupported arguments during migration

Use _UpgradeSerializedRuntime to replace the unsupported command line
arguments with their working counterparts. This will make
already-running instances migrateable to 3.1, cross-version migration
bugs aside.

This is part of #1338.

Signed-off-by: Apollon Oikonomopoulos <ed81ed0a45ccd5c8869bda52e38353a6299ee39e@dmesg.gr>

mbakke/ganeti,mbakke/ganeti,ganeti/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti/ganeti