[0109] Added gossip menus for all alchemy trainers

* Reverted gossip menus for alchemy trainers to what they were in
classic
* Added conditions for alchemy 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