Merge branch 'Topic/1598-speedupQuerying' into 'Product/1549-speedupQuerying'

Topic/1598 speedup querying

See merge request !37

src/Metadata/Controllers/MetadataController.cs

@@ -43,9 +43,8 @@ namespace Coscine.Api.Metadata.Controllers
         [HttpGet("[controller]/profiles/")]
         public IActionResult GetProfiles()
         {
-            var graphUris = _rdfStoreConnector.ListGraphs();
-
-            return Json(new JArray(graphUris.Select(x => x.ToString()).Where(x => x.StartsWith(ApplicationProfileUrl))));
+            var applicationProfiles = _rdfStoreConnector.GetApplicationProfiles();
+            return Json(new JArray(applicationProfiles));
         }
 
         /// <summary>