2867 Fixes a problem with passing unicode to url_for

Forces the file_url to be ascii as it appears that for some reason, and only
occassionally OFS returns unicode instead of str.  We don't want to fix OFS
as it is scheduled for removal and we can fix routes as it is already out of
date.

ckan/controllers/storage.py

@@ -187,7 +187,7 @@ def file(self, label):
             fapp = FileApp(filepath, headers=None, **headers)
             return fapp(request.environ, self.start_response)
         else:
-            h.redirect_to(file_url)
+            h.redirect_to(file_url.encode('ascii','ignore'))
 
 
 class StorageAPIController(BaseController):