Fix broken logic for Show more facet links

cc @johnmartin

The whole thing is pretty broken on core, but this template was even
more broken :). The last item of the facets was not found and the Show
more link did not appear. In order to make the case where there are
exactly 10 items, search.facets.default=11 is required in the ini file,
due to h.get_facet_items_dict ignoring the provided limit param.
Organisation, not Organization
Keep visibility value on form errors

Fixed in core with okfn/ckan#1265
Only show issues filter to sysadmins
Merge branch 'ckan-2.x' of github.com:okfn/ckanext-iati into ckan-2.x