Allow, cleanup and display:

• OD Artist link for MB Artist entity
• OD Expression link for MB Work entity
• OD Performance link for MB Recording entity

OD URL pattern is similar to the one of MB: {{}}FQDN/entity-type/UUID, e.g. : http://overture.doremus.org/artist/269cec9d-5025-3a8a-b2ef-4f7acb088f2b

(OD Recording and Score are still work-in-progress and can be ignored for now.)