The debug configuration group is not registered

The debug option group is not properly registered, probably because of
in-properly solved merge conflict.

This change fixes it.

Change-Id: I0ebe0aee9ed11d70418827d504ee5e5fb05fd5d9
diff --git a/tempest/config.py b/tempest/config.py
index 71705fb..8421c71 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -702,6 +702,7 @@
         register_stress_opts(cfg.CONF)
         register_scenario_opts(cfg.CONF)
         register_service_available_opts(cfg.CONF)
+        register_debug_opts(cfg.CONF)
         self.compute = cfg.CONF.compute
         self.identity = cfg.CONF.identity
         self.images = cfg.CONF.image
@@ -715,6 +716,7 @@
         self.stress = cfg.CONF.stress
         self.scenario = cfg.CONF.scenario
         self.service_available = cfg.CONF.service_available
+        self.debug = cfg.CONF.debug
         if not self.compute_admin.username:
             self.compute_admin.username = self.identity.admin_username
             self.compute_admin.password = self.identity.admin_password