Paginate packages list using 'next_marker' attribute

Organize getting multiple packages in way similar to
pytnon-glanceclient (see http://tinyurl.com/qxqub5w) so it supports
paginating complex query results.

This commit requires https://review.openstack.org/#/c/93900/ to work.

Change-Id: I2477999d03e18d055b3308ec3d03d2782d20bdd3
Implements: blueprint app-catalog-pagination
Merge "Paginate packages list using 'next_marker' attribute"