added ability to pass cached tweets (raw json from twitter api)

Hi, 

I'm the author of django-switter - a twitter api proxy for Django (https://bitbucket.org/grucha/django-switter/)

I use cached tweets to render tweets at page load time without any additional http request.

Could you please merge this pull request so other twitter api proxies can use it too (and so I don't have to use forked version of jquery.tweet in my proxy).

Best regards,
Sylwester Gruszka