Port to argparse based cfg

Import latest cfg from oslo-incubator with these changes:

 Add deprecated --logdir common opt
 Add deprecated --logfile common opt.
 Allow nova and others to override some logging defaults
 Fixing the trim for ListOp when reading from config file
 Fix set_default() with boolean CLI options
 Improve cfg's argparse sub-parsers support
 Hide the GroupAttr conf and group attributes
 Fix regression with cfg CLI arguments
 Fix broken --help with CommonConfigOpts
 Fix ListOpt to trim whitespace
 updating sphinx documentation
 Don't reference argparse._StoreAction
 Fix minor coding style issue
 Remove ConfigCliParser class
 Add support for positional arguments
 Use stock argparse behaviour for optional args
 Use stock argparse --usage behaviour
 Use stock argparse --version behaviour
 Remove add_option() method
 Completely remove cfg's disable_interspersed_args()
 argparse support for cfg

The main cfg API change is that CONF() no longer returns the un-parsed
CLI arguments. To handle these args, you need to use the support for
positional arguments or sub-parsers.

Switching nova-manage to use sub-parser based CLI arguments means the
following changes in behaviour:

 - no more lazy matching of commands - e.g. 'nova-manage proj q' will
   no longer work. If we find out about common abbreviations used in
   peoples' scripts, we can easily add those.

 - the help output displayed if you run nova-manage without any args
   (or just a category) has changed

 - 'nova-manage version list' is no longer equivalent to
   'nova-manage version'

Change-Id: I19ef3a1c00e97af64d199e27cb1cdc5c63b46a82

bin/nova-clear-rabbit-queues

@@ -48,12 +48,18 @@ from nova.openstack.common import log as logging
 from nova.openstack.common import rpc
 
 
-delete_exchange_opt = cfg.BoolOpt('delete_exchange',
-                                  default=False,
-                                  help='delete nova exchange too.')
+opts = [
+    cfg.MultiStrOpt('queues',
+                    default=[],
+                    positional=True,
+                    help='Queues to delete'),
+    cfg.BoolOpt('delete_exchange',
+                default=False,
+                help='delete nova exchange too.'),
+]
 
 CONF = cfg.CONF
-CONF.register_cli_opt(delete_exchange_opt)
+CONF.register_cli_opts(opts)
 
 
 def delete_exchange(exch):
@@ -69,8 +75,8 @@ def delete_queues(queues):
         x.queue_delete(q)
 
 if __name__ == '__main__':
-    args = config.parse_args(sys.argv)
+    config.parse_args(sys.argv)
     logging.setup("nova")
-    delete_queues(args[1:])
+    delete_queues(CONF.queues)
     if CONF.delete_exchange:
         delete_exchange(CONF.control_exchange)