Move search returndoctype definitions to a centralized location
Currently, the returndoctypes for each skin are defined separately. These should be moved to a centralized locate so they only need to be changed once for all skins.
Note that there are several different strategies for defining the returndoctypes including:
-- as hidden form fields
-- using java script
-- defining in a url. This strategy also has several different forms including plain html url, html encoded url and hex encoded url.
All of these need to be handled.