Return config name in Arena arenaName() method.

This is really just an internal change, since the `arenaName()` method
is likely not used anywhere. If it is, however, it shouldn't be depended
on as an identifier anyway, so I'm confident that removing it won't mess
up anything that doesn't need a rework anyway.

src/main/java/com/garbagemule/MobArena/ArenaImpl.java

@@ -1454,7 +1454,7 @@ public class ArenaImpl implements Arena
     @Override
     public String arenaName()
     {
-        return MAUtils.nameConfigToArena(name);
+        return name;
     }
 
     @Override