fixing category.get_absolute_url to be looked up rather than hard coded, allowing for overrides to work to use some other name than category for the url.  Also fixing improper chained filters.  Chaining filters is an OR operation, and we wanted an AND operation
fixing category.get_absolute_url to be looked up rather than hard coded, allowing for overrides to work to use some other name than category for the url.  Also fixing improper chained filters.  Chaining filters is an OR operation, and we wanted an AND operation

--HG--
extra : convert_revision : svn%3Aa38d40e9-c014-0410-b785-c606c0c8e7de/satchmo/trunk%401514

dokterbob/satchmo,Ryati/satchmo,dokterbob/satchmo,ringemup/satchmo,twidi/satchmo,twidi/satchmo,Ryati/satchmo,ringemup/satchmo