Fixed cp_menu for custom domains pintoing to / #2685

Menu add item was broken for custom domains looking to add a home button.  There was nothing after the domain, so the menu check returned false.  When I added <front> that didn't work either since it was run through check_url.

This fixes the problem locally.
Merge pull request #2743 from openscholar/2685-cp_menu

Fixed cp_menu for custom domains pintoing to / #2685