Allow players to track both herbs and minerals at the same time

PR as [requested](http://www.trinitycore.org/f/topic/9390-patch-allow-track-herbs-and-minerals-at-same-time-updated-22-11-2013/#entry68082)

__Note:__

For documentation sake, [here](http://www.trinitycore.org/f/topic/9390-patch-allow-track-herbs-and-minerals-at-same-time-updated-22-11-2013/#entry61754) is a useful macro to allow players to toggle both trackers on / off. Just open the spoiler in the post.
Wouldn't the checks that already exist return false somewhere else? I'm not familiar with aura code.