fix: register Web API explorer for sandbox

F4SDM42WebApi/DependencyRegistrator.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Web.Http;
+using System.Web.Http.Description;
+
+using Matrix42.Hosting.Contracts;
+
+namespace C4IT.F4SD.Properties
+{
+    public sealed class DependencyRegistrator : DependencyRegistratorBase, IDependencyRegistrator
+    {
+        public void Register(IDependencyContainer container, IDependencyResolver resolver)
+        {
+            container.RegisterSingletonType<IApiExplorer>((Type _) => new ApiExplorer(new HttpConfiguration()));
+        }
+    }
+}