CLOUDSTACK-2670. Migrate volume doesn't allow migration of volumes of a stopped vm.
The findStoragePoolsForMigration and migrateVolume api were explicitly blocking moving
a volume if the instance to which it was attached was stopped. Updated the check for
the same.
CLOUDSTACK-4146, CLOUDSTACK-4147: Fix KVM snapshot upgrade.
when migrating KVM snapshot path, CONCAT is not required. back_snap_id is complete path for KVM snapshots