Add interface for listing security groups of an instance

This is already available in nova but not exposed via client.

* novaclient/v1_1/servers.py:
   New interface to list security groups of an instance.

* novaclient/v1_1/shell.py:
   New sub command list-secgroup.

* novaclient/tests/v1_1/fakes.py,
  novaclient/tests/v1_1/test_servers.py,
  novaclient/tests/v1_1/test_shell.py:
   Add corresponding tests.

Implements: blueprint servers-list-secgroup

Change-Id: I505bcffdbb15b84bfd73cae5ef5a8fb9c69bd7b9
Suport instance list pagination in novaclient, Part I

Bug 1209242

nova-api has supported pagination for long. A marker and limit
option could be passed to nova-api to get a slice of instances.
It makes sense to enable this feature in novaclient, so that
horizon could use it for pagination supporting. Modification to
shell.py would be submitted in a separate patch.

Further change will also pass 'sort_key' and 'sort_dir' to
nova-api, as long as nova supports this.

This is part of blueprint support-pagination-for-instance-list

Change-Id: Ieb5f2c1eb31b9f7e95b62b51ea7dc338e3970d04
Merge "Add interface for listing security groups of an instance"