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