Use oslo.config generator

Replace usage of old incubator configuration generator by the
oslo.config tool.

tools/config/generate_sample.sh has been replaced by tox -egenconfig.

heat_integrationtests/generate_sample.sh has been replaced by
oslo-config-generator
--config-file=heat_integrationtests/config-generator.conf

Change-Id: I6d95df203b556c8ec2088d40a446427f7087b9a7
diff --git a/common/config.py b/common/config.py
index 71fabe1..562b80b 100644
--- a/common/config.py
+++ b/common/config.py
@@ -11,7 +11,6 @@
 #    under the License.
 
 import os
-import sys
 
 from oslo.config import cfg
 
@@ -108,7 +107,5 @@
     return conf
 
 
-if __name__ == '__main__':
-    cfg.CONF = init_conf(False)
-    import heat.openstack.common.config.generator as generate
-    generate.generate(sys.argv[1:])
+def list_opts():
+    yield None, IntegrationTestGroup