consider rpc implementation

oauth3.core.js

@@ -81,6 +81,9 @@
       action: 'directives'
     , state: core.utils.randomState()
     , redirect_uri: opts.appUrl + (opts.appCallbackPath || '/.well-known/oauth3/callback.html')
+    , response_type: 'rpc'
+    , _method: 'GET'
+    , _pathname: '.well-known/oauth3/directives.json'
     , debug: opts.debug || undefined
     };