core: import/export from template version

Add template version to import and export of vm and template.

http://www.ovirt.org/index.php?title=Features/Template_Versions

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1037478
Change-Id: I3dd434f5857a707f12508ebb6ab20e46a4f1be3c
Signed-off-by: Omer Frenkel <ofrenkel@redhat.com>