Added drf-ujson-renderer to renderers docs

drf-ujson-renderer is a third party renderer that implements JSON renderering using UltraJSON
Merge pull request #1220 from hzy/patch-1

Added drf-ujson-renderer to renderers docs
Add queryset aggregates to allowed fields in OrderingFilter
Merge branch 'master' into allow-aggregate-ordering
Bump version
Undo version bump
Merge pull request #1224 from alexjg/allow-aggregate-ordering

Allow aggregate ordering
Add Alex Good to credits (Whoop!)
Merge pull request #1226 from alexjg/master

Add Alex Good to credits (Whoop!)