example.html: Fix selectPackaging call in packaging-select widget
example.html: Fix selectPackaging call in packaging-select widget

packaged_product wasn't defined, so change's weren't doing anything
useful in selectPackaging.  The fixed version works like this:

1. User selects an option in the drop-down
2. Angular sets product.code (because it's ng-model)
3. Angular triggers ng-change
4. selectPackaging fires with the new code

I'd broken this in ac2181f8 (azure-providers.js: Add PackagedProduct
and update associated APIs, 2015-02-23).  That was a big change, and I
broke a few of other things too, grep the logs for ac2181f ;).

azurestandard/azure-angular-providers,azurestandard/azure-angular-providers