Core/DBC: Implemented achievement_dbc db table for filling in missing achievements and added sample data

src/server/game/DataStores/DBCfmt.h

@@ -20,6 +20,8 @@
 #define TRINITY_DBCSFRM_H
 
 const char Achievementfmt[]="niixssssssssssssssssxxxxxxxxxxxxxxxxxxiixixxxxxxxxxxxxxxxxxxii";
+const std::string CustomAchievementfmt="pppaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaapapaaaaaaaaaaaaaaaaaapp";
+const std::string CustomAchievementIndex = "ID";
 const char AchievementCriteriafmt[]="niiiiiiiixxxxxxxxxxxxxxxxxiiiix";
 const char AreaTableEntryfmt[]="iiinixxxxxissssssssssssssssxixxxxxxx";
 const char AreaGroupEntryfmt[]="niiiiiii";