Update to latest version of DRF2.
Merge branch 'master' into wallpost-reactions-api
Some fixes after review

Order reactions ascending by date
Fix pre_save to set author/editor properly for reactions
Removed code that shouldnt be there int the first place
PEP8
Merge branch 'wallpost-reactions-api' of github.com:onepercentclub/bluebottle into wallpost-reactions-api