Removes unicode 'u' response for "cinder get-capabilities"

The output of "cinder get-capabilities" command returns
unicoded response. But it would appear from the utils
class that setting formatters will go through the
capabilities dict and make sure all values are properly
string formatted. Therefore added formatters to return
string formatted response.

Added formatters=sorted(prop.keys()) line instead of
static values as suggested by the reviewer, to avoid
tying server knowledge to the client and also any
update on the server side would easily reflect here.

Closes-bug: #1680444
Change-Id: Ie38236db364d59ddab42cb925d0435777b0ffe86

cinderclient/tests/unit/v2/fakes.py

@@ -1278,9 +1278,9 @@ class FakeHTTPClient(base_client.HTTPClient):
                 'storage_protocol': 'iSCSI',
                 'properties': {
                     'compression': {
-                        'title': 'Compression',
-                        'description': 'Enables compression.',
-                        'type': 'boolean'},
+                        u'title': u'Compression',
+                        u'description': u'Enables compression.',
+                        u'type': u'boolean'},
                 }
             }
         )

cinderclient/v2/shell.py

@@ -2375,7 +2375,8 @@ def do_get_capabilities(cs, args):
 
     prop = infos.pop('properties', None)
     utils.print_dict(infos, "Volume stats")
-    utils.print_dict(prop, "Backend properties")
+    utils.print_dict(prop, "Backend properties",
+                     formatters=sorted(prop.keys()))
 
 
 @utils.arg('volume',