Add caster guid to pet_aura table.

This prevents duplicate key and transaction completion fail on pet save, if pet has same aura from two different casters present.

This closes (already closed) issue https://github.com/TrinityCore/TrinityCore/issues/10529

sql/updates/characters/2015_10_07_00_characters.sql

@@ -0,0 +1,3 @@
+ALTER TABLE `pet_aura`
+DROP PRIMARY KEY,
+ADD PRIMARY KEY (`guid`,`casterGuid`,`spell`,`effectMask`);