Build fixes following .NET Core 2.0 update

Author: SteveSandersonMS

samples/angular/MusicStore/Startup.cs

@@ -28,7 +28,7 @@ public void ConfigureServices(IServiceCollection services)
             });
 
             // Add EF services to the service container
-            services.AddEntityFramework()
+            services
                 .AddEntityFrameworkSqlite()
                 .AddDbContext<MusicStoreContext>(options => {
                     options.UseSqlite("Data Source=music-db.sqlite");

samples/react/MusicStore/Startup.cs

@@ -30,7 +30,7 @@ public void ConfigureServices(IServiceCollection services)
             });
 
             // Add EF services to the service container
-            services.AddEntityFramework()
+            services
                 .AddEntityFrameworkSqlite()
                 .AddDbContext<MusicStoreContext>(options => {
                     options.UseSqlite("Data Source=music-db.sqlite");