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
CLOUDSTACK-3842: G11N: SC: Some regression issues occurred on build#4.2-256.
CLOUDSTACK-4187: 2.2.1 - 4.2 Upgrade: Few Guest OS Types information is inconsistent on the Upgraded Setup when compared with the fresh 4.2 Installation.