Enable cmd/api & cmd/conductor to be launched directly

This will be needed for functional testing, so we can execute them with:
  python -m ironic.cmd.api
  python -m ironic.cmd.conductor

Change-Id: I2f201ee1f6517879fec6da4e6f40a6155763d979
Partial-Bug: #1491670

ironic/cmd/api.py

@@ -64,3 +64,7 @@ def main():
         wsgi.serve_forever()
     except KeyboardInterrupt:
         pass
+
+
+if __name__ == '__main__':
+    sys.exit(main())

ironic/cmd/conductor.py

@@ -45,3 +45,7 @@ def main():
 
     launcher = service.launch(CONF, mgr)
     launcher.wait()
+
+
+if __name__ == '__main__':
+    sys.exit(main())