Fix remote cmds cleanup

When --remote-copy and --remote-exec are provided,
args.remote_cmds_cleanup_pattern is not set.

This patches fixes the evaluation of args.remote_cmds_cleanup_pattern
and prevents cdist from throwing an exception when --remote-copy
and --remote-exec are used.

cdist/config.py

@@ -270,7 +270,7 @@ class Config(object):
             remote_copy = args.remote_copy_pattern.format(control_path)
         else:
             remote_copy = args.remote_copy
-        if args.remote_cmds_cleanup_pattern:
+        if 'remote_cmds_cleanup_pattern' in args:
             remote_cmds_cleanup = args.remote_cmds_cleanup_pattern.format(
                 control_path)
         else: