Fix: Graphs with special characters now work

(coscine/issues#626)

src/Project/Controllers/MetadataController.cs

@@ -112,7 +112,8 @@ namespace Coscine.Api.Project.Controllers
             if (_resourceModel.HasAccess(user, resource, UserRoles.Owner, UserRoles.Member))
             {
                 var id = _metadataModel.GenerateId(resourceId, filename, version);
-                var graph = _util.GetGraph(id);
+                var uri = _metadataModel.CreateUri(id);
+                var graph = _util.GetGraph(uri);
                 return Json(JToken.Parse(VDS.RDF.Writing.StringWriter.Write(graph, new RdfJsonWriter())).ToString());
             }
             else
@@ -126,7 +127,7 @@ namespace Coscine.Api.Project.Controllers
         {
             var innerBlock = ObjectFactory<JToken>.DeserializeFromStream(Request.Body);
             var graphName = _metadataModel.GenerateId(resourceId, filename, version);
-            var graphNameUri = new Uri(graphName);
+            var graphNameUri = _metadataModel.CreateUri(graphName);
             var json = new JObject
             {
                 [graphName] = innerBlock