Add feature flags in config to enable tests conditionally

This would allow to skip tests if a required feature is not
enabled in the config.

Change-Id: Icb699497c1d348354b6a5880ea3e4ab2de6e059b
diff --git a/heat_tempest_plugin/plugin.py b/heat_tempest_plugin/plugin.py
index acf4fc7..6926691 100644
--- a/heat_tempest_plugin/plugin.py
+++ b/heat_tempest_plugin/plugin.py
@@ -34,7 +34,11 @@
                                   heat_config.ServiceAvailableGroup)
         config.register_opt_group(conf, heat_config.heat_group,
                                   heat_config.HeatGroup)
+        config.register_opt_group(conf, heat_config.heat_features_group,
+                                  heat_config.HeatFeaturesGroup)
 
     def get_opt_lists(self):
         return [(heat_config.heat_group.name,
-                 heat_config.HeatGroup)]
+                 heat_config.HeatGroup),
+                (heat_config.heat_features_group.name,
+                 heat_config.HeatFeaturesGroup)]