Added scopes to 2.0 apis

src/main/java/org/scribe/oauth/OAuth20ServiceImpl.java

@@ -32,6 +32,7 @@ public class OAuth20ServiceImpl implements OAuthService
     request.addQuerystringParameter(OAuthConstants.CLIENT_SECRET, config.getApiSecret());
     request.addQuerystringParameter(OAuthConstants.CODE, verifier.getValue());
     request.addQuerystringParameter(OAuthConstants.REDIRECT_URI, config.getCallback());
+    if(config.hasScope()) request.addQuerystringParameter(OAuthConstants.SCOPE, config.getScope());
     Response response = request.send();
     return api.getAccessTokenExtractor().extract(response.getBody());
   }