Fix namespacing issues for links in render helpers

- d3c0e0d8 removed the ability to use namespaces on the sortable tree helper. This reinstates that capability, but also adds consistent rendering *and* namespacing for all render helpers.
- ce696f3a meant to clarify that a `show` link was not being used for a `delete` link, but neglected to update in all the helpers. This PR also addresses that issue.