Refactor error handling. Add 404 page

Website/Controllers/ErrorController.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Diagnostics;
+using Microsoft.AspNetCore.Mvc;
+using Website.ViewModels;
+
+namespace Website.Controllers
+{
+	public class ErrorController : Controller
+	{
+
+		public IActionResult BlowUp() {
+			throw new Exception();
+		}
+
+		[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
+		public IActionResult ServerError()
+		{
+			return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
+		}
+
+		[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
+		public IActionResult PageNotFound()
+		{
+			return View();
+		}
+	}
+}