[0169] Added gossip menus for all first aid trainers

* Reverted gossip menus for first aid trainers to what they were in
classic
* Added conditions for first aid trainers to handle this change
In classic and especially prior to patch 2.3, crafting tradeskills where
taught by trainers splitted in several tiers.
Every tier corresponded to one of the four level of a skill (Apprentice,
Journeyman, Expert, Artisan) and trainers can only teach tiers below
their own: Journeyman -> Apprentice, Expert -> Journeyman,
Artisan -> Expert, Master -> Artisan. When player reached the same tier
as a trainer, the gossip of this trainer would change to indicates where
to train for the next tier
Source regarding this change:
http://www.wowwiki.com/Patch_2.3#Profession