Fix checkstyle on unused import

Author: PseudoKnight

src/main/java/com/laytonsmith/core/functions/MobManagement.java

@@ -44,7 +44,6 @@
 import com.laytonsmith.core.exceptions.CRE.CREBadEntityTypeException;
 import com.laytonsmith.core.exceptions.CRE.CRECastException;
 import com.laytonsmith.core.exceptions.CRE.CREFormatException;
-import com.laytonsmith.core.exceptions.CRE.CREIllegalArgumentException;
 import com.laytonsmith.core.exceptions.CRE.CRELengthException;
 import com.laytonsmith.core.exceptions.CRE.CRERangeException;
 import com.laytonsmith.core.exceptions.CRE.CREThrowable;