add Previous link to Admin > Images table

The Glance API supports a sort direction which we can use to paginate back

The Prev href tag contains a marker id of the first item in the table.
When clicked, a GET API call is made, passing in this marker and the sort_dir='asc'
This will return the previous page's data.  Then we have to re-sort the data because
it is ordered backwards.  We use the default sort_key='created_by' for this.

Once the patch #1252649 is restored, we can add the same behavior to Project > Images.

If we are able to get the consistency across the APIs to include the sort_dir, then we can
bring Prev to the other project tables as well.  There are some blueprints to enhance
API capabilities in this area.

Change-Id: I3e7c6a2db595838dbdff595dc8f0fdda288b6bcf
Partial-Bug: #1263142
Partial-Bug: #1282987
Partially-implements: blueprint pagination-add-prev-link
Merge "add Previous link to Admin > Images table"