Remove the feature link from the trash and spam pages

Applies to https://github.com/GigaOM/gigaom/issues/5248

Using the global set in `bSocial_Comments_Feedback_Table` to filter for the trash and spam pages and bail before outputting the feature link.
https://github.com/misterbisson/bsocial-comments/pull/97#discussion_r17484937

> I've been increasingly using whitelists rather than blacklists. They allow you to assert that you're specifically supporting something. Imagine what happens when a new status is introduced...

https://github.com/misterbisson/bsocial-comments/pull/97#discussion_r17485006

> I don't know if it's truly faster, but when comparing two or more values for a single variable, I prefer to use `in_array()` or `switch()`.