Remove project id in ViewBuilder alternate link

Clearly nobody really uses the "application/vnd.openstack.image"
links in the returned results from GET /v2/{tenant}/images
REST API call, since the link URI returned in it is wrong.

Glance URIs do *not* contain a project or tenant in the URI
structure like Nova's REST API URIs do, but _get_alternate_link()
method of the image ViewBuilder tacks it on improperly:

Change-Id: I4ccb5628569c60026a1772df0794ac0271c48db3
Closes-Bug: #1343080
Merge "Remove project id in ViewBuilder alternate link"