WSDL: http://xyz.example.com/__/webservices/listings?wsdl
This web service is used to retrieve data from the lisings module. This includes
retrieving listings, listing types and categories.
Argument 1: Module_Listings_Webservices_Options_GetCategories
The options to determine which categories to return
Returns: Array of Module_Listings_Webservices_Category
This method returns a list of categories based on the specified options.
