Fix for fatal VIP is reporting.

https://github.com/GigaOM/gigaom/issues/5663
`sorted_terms` already has that defaults array.  We should add a filter to the `$args` used in `sorted_terms` and hook to that from the child theme (perhaps).  Or use a config file to drive the defaults.  Then we wouldn't need to bake in the custom `taxonomies` array.