Add AgedBrieItem with updateQuality logic

Java/src/main/java/com/gildedrose/items/AgedBrieItem.java

@@ -0,0 +1,16 @@
+package com.gildedrose.items;
+
+import com.gildedrose.Item;
+
+public class AgedBrieItem extends GildedItem {
+    public AgedBrieItem(Item item) { super(item); }
+
+    @Override
+    public void updateQuality() {
+        increaseQuality(1);
+        decreaseSellIn();
+        if (item.sellIn < 0)
+            increaseQuality(1);
+    }
+}
+