Add --sort-key and --sort-dir to image-list

The --sort-key and --sort-dir CLI options allow users to control the
field and direction by which their images are sorted in an image-list
operation. The previous default sort behavior of sorting by ID asc has
been preserved.

Fixes bug 1082957.

Change-Id: I1d3664219c275b0379fe176f8288d6ffae0dffbe

glanceclient/common/utils.py

@@ -54,7 +54,7 @@ def print_list(objs, fields, formatters={}):
                 row.append(data)
         pt.add_row(row)
 
-    print pt.get_string(sortby=fields[0])
+    print pt.get_string()
 
 
 def print_dict(d):