[0648] Fixed respawn time of three bosses in Ruins of Ahn'Qiraj

* Fixed respawn time of three bosses in Ruins of Ahn'Qiraj
- Moam
- General Rajaxx
- Ossirian the Unscarred
[0649] Added fire immunity to creature 11668

* Added fire immunity to creature 11668 (Firelord) in Molten Core:
- Made room in creature's AI script to add the immunity spell cast at
spawn
- Added new script to make creature 11668 (Firelord) cast "Immunity:
Fire" at spawn