rename "vault" to "web"

src/Web/Startup.cs

@@ -0,0 +1,16 @@
+using System;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Bit.Web
+{
+    public class Startup
+    {
+        public void ConfigureServices(IServiceCollection services) { }
+
+        public void Configure(IApplicationBuilder app)
+        {
+            app.UseFileServer();
+        }
+    }
+}