Rework versioning support to allow it to be one or off.

Turns out versioning isn't quite ready for prime time, so let's have a
fallback plan shall we?

tailbone/templates/departments/crud.mako

@@ -8,7 +8,7 @@
   % elif form.updating:
       <li>${h.link_to("View this Department", url('department.read', uuid=form.fieldset.model.uuid))}</li>
   % endif
-  % if not form.creating and request.has_perm('department.versions.view'):
+  % if version_count is not Undefined and request.has_perm('department.versions.view'):
       <li>${h.link_to("View Change History ({0})".format(version_count), url('department.versions', uuid=form.fieldset.model.uuid))}</li>
   % endif
 </%def>