core: add template version related fields to vm and template

for templates, added templateVersionNumber, templateVersionName and baseTemplateId
fot VMs, added useLatestVersion
these fields are used for supporting templates versions,
as documented in the Template Versions feature page

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

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1037478
Change-Id: I08f13eee5609525880a92fc81c9fd3cb1d2ba62d
Signed-off-by: Omer Frenkel <ofrenkel@redhat.com>