Implements the 'Implicit Grant'.
A typical call looks like
/oauth2/authorize/?client_id=an_existing_client_id=token&redirect_uri=the_client_redirect_uri

Implements the 4.2.2 "Access Token Response" specifications
Merge branch 'master' of https://github.com/kusamau/django-oauth2-provider
A 'response_type' == 'token' must return a json object leaving the
redirect_uri to the client