Define the new pagination API in storage base.
Define the new pagination API in storage base.

1. Listing operations interactively yield an iterator and a marker;
2. Listing queue now only support forward listing.

Change-Id: I6fe57228344518c16757b2a4175abb7bf529b513
Implements: blueprint storage-base

openstack/zaqar,rackerlabs/marconi,openstack/zaqar,openstack/zaqar,openstack/zaqar