fixes #6472 / BZ 1113230 - content view filter - fix issue where filter not available

On the content view filter edit screens, it was possible for a
"really fast" user to click links that utilized the filter, before
it had actually been loaded.  Eg. Open a filter and click the 'Add' tab.

This small change will ensure that we do not render the content of the
filter edit, before the filter is actually available.
Merge pull request #4379 from bbuckingham/issue-6472

fixes #6472 / BZ 1113230 - content view filter - fix issue where filter not available