Extend the item key mapping of SCA webstore

Extend the item key mapping file using the configuration as dependency.
In this code, the methods “_comparePriceAgainst” and “_comparePriceAgainstFormated” are modified to change the compare price level to be displayed in the webstore.

Configuration.itemKeyMapping = Configuration.itemKeyMapping || {};
  _.extend(Configuration.itemKeyMapping,
 {
    _comparePriceAgainst: function _comparePriceAgainst(item)
    {
	return item.get('pricelevel300');
    }
 , _comparePriceAgainstFormated: function _comparePriceAgainstFormated(item)
   {
	return item.get('pricelevel300_formatted');
   }		  
});