Updated requirements of django-celery to >=3.0.11
Merge branch 'master' of github.com:ASKBOT/askbot-devel
Fix deprecation warning in HttpResponse

Replace `mimetype` by `content_type` in `HttpResponse` attributes.
see:
<https://docs.djangoproject.com/en/1.4/ref/request-response/#id5>
Merge pull request #250 from BenjaminABEL/master

Updated requirements of django-celery to >=3.0.11