Fixed drush custom domain.  Added list feature.  #2297

Drush vrd was deleting from spaces_overrides, but not purl.  Fixed that.
Also added drush vrl which gets a list of id, domain, name.  I figured if you needed to know the nid to remove a vsite's domain, there should be an easy way to find that nid.
Merge pull request #2356 from openscholar/2297-drush_vsite_domain

Fixed drush custom domain.  Added list feature.  #2297