Adds the ability to sort images with multiple keys

Adds client code to consume API modified in change
Ib7a6aeb2df3bc5d23fe8e070290b5bfcab00c0f5

Extends CLI for v2 with multiple sort keys
Example:
glance --os-image-api-version 2 image-list --sort-key name --sort-key size

Implements-blueprint: glance-sorting-enhancements
Change-Id: If79779a4c52c8dc5c4f39192d3d247335a76ba24
DocImpact
Closes-Bug: 1221274

glanceclient/v2/shell.py

@@ -16,6 +16,7 @@
 from glanceclient.common import progressbar
 from glanceclient.common import utils
 from glanceclient import exc
+from glanceclient.v2 import images
 from glanceclient.v2 import tasks
 import json
 import os
@@ -124,6 +125,12 @@ def do_image_update(gc, args):
            help='Displays images that match the checksum.')
 @utils.arg('--tag', metavar='<TAG>', action='append',
            help="Filter images by a user-defined tag.")
+@utils.arg('--sort-key', default=[], action='append',
+           choices=images.SORT_KEY_VALUES,
+           help='Sort image list by specified fields.')
+@utils.arg('--sort-dir', default='asc',
+           choices=images.SORT_DIR_VALUES,
+           help='Sort image list in specified direction.')
 def do_image_list(gc, args):
     """List images you can access."""
     filter_keys = ['visibility', 'member_status', 'owner', 'checksum', 'tag']
@@ -141,6 +148,11 @@ def do_image_list(gc, args):
         kwargs['limit'] = args.limit
     if args.page_size is not None:
         kwargs['page_size'] = args.page_size
+    if args.sort_key:
+        kwargs['sort_key'] = args.sort_key
+    else:
+        kwargs['sort_key'] = ['name']
+    kwargs['sort_dir'] = args.sort_dir
 
     images = gc.images.list(**kwargs)
     columns = ['ID', 'Name']