Add user registration emails + email infrastructure (#150)

* Add email functionality

* Add email template project and rendering service

* Update email template dir structure

* Add email header and footer components for user registration template

* update example env

* Refactor email templates namespace and components

* Format email dir

src/Core/API/API.Specs/TestApiFactory.cs

@@ -1,7 +1,10 @@
 using System.Collections.Generic;
+using API.Specs.Mocks;
+using Infrastructure.Email;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace API.Specs
 {
@@ -10,6 +13,20 @@ namespace API.Specs
         protected override void ConfigureWebHost(IWebHostBuilder builder)
         {
             builder.UseEnvironment("Testing");
+
+            builder.ConfigureServices(services =>
+            {
+                // Replace the real email service with mock for testing
+                var descriptor = services.SingleOrDefault(
+                    d => d.ServiceType == typeof(IEmailProvider));
+
+                if (descriptor != null)
+                {
+                    services.Remove(descriptor);
+                }
+
+                services.AddScoped<IEmailProvider, MockEmailProvider>();
+            });
         }
     }
 }