added guardian as optional requirement, stubbed out object-level permission class
some properly failing tests, set up for standard permissions
necessary test settings for guardian
first pass at object level permissions and tests
switch to a dedicated filter for read list object permissions
removed unnecessary guardian req and view.action parsing
better doc for object permissions, drop redundant has_permission call
Add order_by to the AutoFilterSet

`AutoFilterSet` should contains `order_by` set to all by default.
Merge branch 'master' of git://github.com/bwreilly/django-rest-framework into bwreilly-master
Tweaks and docs to object-level model permissions.
Updated release notes
Add Django Guardian to travis testing
Added @bwreilly for awesome work on #1093.  Thanks!!!
Version 2.3.8
small typo correction on ViewSet example code
Merge pull request #1099 from diegoponciano/patch-1

small typo correction on ViewSet example code
Fix django guardian link
Merge branch 'master' of https://github.com/tomchristie/django-rest-framework
Merge pull request #1097 from mociepka/add_default_order_by_in_filtering

Add order_by to the AutoFilterSet
Note on '.model' as default only, with 'serializer_class', and 'queryset' attributes prefered.  Closes #1100