[c2939] Ulduar conditions and Leviathan achievements

Requires CMangos [c12752]

* This will allow hard mode loot conditions for the bosses which currently support this
* Allow vehicles to be used only during the siege event
* Implement Leviathan hard mode achievements

(based on commit SD2-WotLK [2936] - 709f8ff)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>