Make object option dependent on container in usage strings

In usage messages, it only makes sense to have an
object option if the container option has been specified.
Fixes the parentheses to indicate this.

Change-Id: I550ba99879ea6ce5489617a94cec36b66be270c8
Related-Change: Ie84a90eb0278dd2cdf5775948572bb140f8d2c4b

swiftclient/shell.py

@@ -58,7 +58,7 @@ def immediate_exit(signum, frame):
 st_delete_options = '''[--all] [--leave-segments]
                     [--object-threads <threads>]
                     [--container-threads <threads>]
-                    [<container>] [<object>] [...]
+                    [<container> [<object>] [...]]
 '''
 
 st_delete_help = '''
@@ -209,7 +209,7 @@ st_download_options = '''[--all] [--marker <marker>] [--prefix <prefix>]
                       [--container-threads <threads>] [--no-download]
                       [--skip-identical] [--remove-prefix]
                       [--header <header:value>] [--no-shuffle]
-                      [<container>] [<object>]
+                      [<container> [<object>] [...]]
 '''
 
 st_download_help = '''
@@ -581,7 +581,7 @@ def st_list(parser, args, output_manager):
 
 
 st_stat_options = '''[--lh]
-                  [<container>] [<object>]
+                  [<container> [<object>]]
 '''
 
 st_stat_help = '''
@@ -655,7 +655,7 @@ def st_stat(parser, args, output_manager):
 st_post_options = '''[--read-acl <acl>] [--write-acl <acl>] [--sync-to]
                   [--sync-key <sync-key>] [--meta <name:value>]
                   [--header <header>]
-                  [<container>] [<object>]
+                  [<container> [<object>]]
 '''
 
 st_post_help = '''