Bring RESTApi closer to ithe imminent keystoneclient.Session

Prepare to use the (soon to be) common Session from keystoneclient
* Rework RESTApi to eventually be a subclass of keystoneclient.Session

Change-Id: I68e610f8b19a3f6267a93f7bf3de54a228be68aa

openstackclient/shell.py

@@ -405,7 +405,10 @@ class OpenStackShell(app.App):
             self.verify = self.options.os_cacert
         else:
             self.verify = not self.options.insecure
-        self.restapi = restapi.RESTApi(verify=self.verify)
+        self.restapi = restapi.RESTApi(
+            verify=self.verify,
+            debug=self.options.debug,
+        )
 
     def prepare_to_run_command(self, cmd):
         """Set up auth and API versions"""