Revert "getting_started.rst: add JSONOAuthLibCore as part of tutorial (#734)"

This reverts commit 392257a.

Author: n2ygk

docs/rest-framework/getting_started.rst

@@ -100,8 +100,6 @@ Also add the following to your `settings.py` module:
 .. code-block:: python
 
     OAUTH2_PROVIDER = {
-        # parses OAuth2 data from application/json requests 
-        'OAUTH2_BACKEND_CLASS': 'oauth2_provider.oauth2_backends.JSONOAuthLibCore',
         # this is the list of available scopes
         'SCOPES': {'read': 'Read scope', 'write': 'Write scope', 'groups': 'Access to your groups'}
     }
@@ -114,10 +112,6 @@ Also add the following to your `settings.py` module:
         )
     }
 
-`OAUTH2_PROVIDER` setting parameter sets the backend class that is used to parse OAuth2 requests.
-The `JSONOAuthLibCore` class extends the default OAuthLibCore to parse correctly
-`application/json` requests.
-
 `OAUTH2_PROVIDER.SCOPES` setting parameter contains the scopes that the application will be aware of,
 so we can use them for permission check.