Merge pull request #4 from dgreisen/a246bfb114141db45e990232d09aa8825174fd77

remove duplicate call to queryset.values
give usefull informations when form validation fails + return 400 status code
Merge pull request #8 from Psycojoker/patch-1

give usefull informations when form validation fails + return 400 status code
Fix README typo
Merge branch 'master' of https://github.com/af/djangbone
mimetype -> content_type