User Displaypool ID instead of assetpath

Matt - This is realted to the recent change you made to allow for the complete removal of site directories. In further testing I found this code caused errors without a site directory. Please review to make sure this does what you expect but I'm basically favoring the local site's contentRenderer and then falling back to the displaypool's. At least one or the other must still exist. 

Another option here would be to test for both locations fileExists on line 131 but it would require some heavier refactoring on the Theme contentRenderer code starting on 138 so I avoided making the change there.