fixes #6059 - add 'product content' tab to content hosts UI

Content hosts now have a 'Product Content' tab on par with what was recently done for activation keys.
Since we know what version of sub-man is installed on a system, it would be great to just not show this message if the correct version is installed.  If its not at the needed version,  warn the user (not just an info box) that this page will not do function properly.