Merge pull request #482 from Iterable/brad/ios-6.3.1

Updated CHANGELOG for iOS 6.3.1

Author: roninopf

CHANGELOG.md

@@ -4,7 +4,15 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## 6.3.1
 #### Added
-- The optional fields from the `trackPurchase` API have been added to the SDK's methods
+- The following properties have been added to the `CommerceItem` class:
+
+  - `sku` - The item's SKU
+  - `itemDescription` - A description of the item
+  - `url` - A URL associated with the item
+  - `imageUrl` - A URL that points to an image of the item 
+  - `categories` - Categories associated with the item 
+
+  Set these values on `CommerceItem` objects passed to the `IterableAPI.trackPurchase` method.
 
 #### Fixed
 - The notification service extension has been re-architected for better reliability