Fixed an issue with converting kits.

src/main/java/com/craftaro/ultimatekits/conversion/Convert.java

@@ -47,7 +47,7 @@ public class Convert {
                 for (ItemStack item : cvt.getItemStacks()) {
                     if (item == null || item.getType() == Material.AIR)
                         continue;
-                    kitObj.getContents().add(new KitItem(item));
+                    kitObj.addItem(new KitItem(item));
                 }
                 kitObj.setDelay(cvt.getDelay());
             }

src/main/java/com/craftaro/ultimatekits/kit/Kit.java

@@ -275,6 +275,10 @@ public class Kit implements Cloneable {
         return this;
     }
 
+    public void addItem(KitItem item) {
+        this.contents.add(item);
+    }
+
     public Kit clone(String key) {
         try {
             Kit newKit = (Kit) super.clone();