[0104] Updated quest_template for many quests

* Fixed required creature for druid quests 6129 (Curing the Sick -
Horde) and 6124 (Curing the Sick - Alliance)
* Fixed quest 6981 (The Glowing Shard) by adding missing gossip script
* Fixed quest 5902 and 5904 (A Plague Upon Thee Horde/Alliance) by
adding missing gossip script
* Added start script for quest 72 (The Legend of Stalvan)
* Backported start scripts from YTDB for:
quest 753 (A Humble Task)
quest 790 (Sarkoth)
quest 947 (Cave Mushrooms)
quest 993 (A Lost Master)
quest 1221 (Blueleaf Tubers)