Fix: update/deletion of Files is possible (coscine/issues#464)

src/Project/Controllers/DataSourceController.cs

@@ -230,7 +230,7 @@ namespace Coscine.Api.Project.Controllers
             else
             {
                 // If the path is null, an empty string is added.
-                string url = $"{_configuration.GetString("coscine/global/waterbutler_url")}{resource.Type.DisplayName.ToLower()}/{path}";
+                string url = $"{_configuration.GetString("coscine/global/waterbutler_url")}{resource.Type.DisplayName.ToLower()}{path}";
 
                 var request = new HttpRequestMessage(HttpMethod.Delete, url);
                 request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", authHeader);