Use dotnet default development certificate for .NET Core 2.x (#381)

src/WireMock.Net/HttpsCertificate/PublicCertificateHelper.cs

@@ -3,6 +3,9 @@ using System.Security.Cryptography.X509Certificates;
 
 namespace WireMock.HttpsCertificate
 {
+    /// <summary>
+    /// Only used for NetStandard 1.3
+    /// </summary>
     internal static class PublicCertificateHelper
     {
         // 1] Generate using https://www.pluralsight.com/blog/software-development/selfcert-create-a-self-signed-certificate-interactively-gui-or-programmatically-in-net

src/WireMock.Net/Owin/AspNetCoreSelfHost.cs

@@ -106,7 +106,7 @@ namespace WireMock.Owin
                         PortUtils.TryExtract(url, out string protocol, out string host, out int port);
                         options.Listen(System.Net.IPAddress.Any, port, listenOptions =>
                         {
-                            listenOptions.UseHttps(PublicCertificateHelper.GetX509Certificate2());
+                            listenOptions.UseHttps(); // PublicCertificateHelper.GetX509Certificate2()
                         });
                     }
 #endif