Adjust sandbox mod_wsgi config to use less resources
Add Solr config to sandbox
Remove MultiFacetedSearch{View,Form}

These classes have been removed in favour of the new search structure
developed for Oscar's demo site.
Use net_stock_level in search index
Rework faceting

The facets are now fully automatic based on the OSCAR_SEARCH_FACETS
setting.
Rename search form to be more generic
Update release notes with search changes
Ensure search results load products in bulk
Cache is_group per instance

This is a performance improvement as it prevents many SQL queries.  The
is_group property is called several times from within the templates and
this change avoids the dupliate queries.