There are few cases that mgt server won't reponse agent's pingcommand timely, or in KVM's case, libvirt won't repsonse in few mintues, which will cause agent reconnect to mgt server, then all the on going tasks on host will fail
fix kvm issue, for windows sever 2008, it will crash without hyperv enlightment featre enabled
CS-21296: hidden snapshot.backup.rightafter, as it's not needed
fix kvm agent upgrade issue: kvm agent needs to use java 7 instead of java 6 after upgrade Reviewed-by: Sheng
there is no transaction context during the mgt server start, thus causing transaction.close will delete op_lock table if aquireinlocktable is called Reviewed-by: Anthony and Min
should not duplicate vm instance id, during the volume migration

Conflicts:
	engine/storage/volume/src/org/apache/cloudstack/storage/volume/VolumeServiceImpl.java
CLOUDSTACK-7683: hold a db lock during vm expunge
system vm image build process, needs to build an old version of qemu image, otherwise, it won't work on RHEL 6