core: sysprep timezone is set as system timezone

Vm.timezone needs to map for every run (i.e. system BIOS timezone - the
one that we sent to qemu command line).
Vm.VmInit.timezone needs to map only for Sysprep use (i.e. first run)

Change-Id: If48c49b7e36d5382965a77c99fd7fa1f5d884578
Bug-Url: https://bugzilla.redhat.com/1088440
Signed-off-by: Shahar Havivi <shaharh@redhat.com>