Allow users to override HttpClientHandler used

Ideally, would be used to circumvent issues surfaced in DotNetDevs#115

Synology/Classes/SynologyHttpClient.cs

@@ -0,0 +1,27 @@
+using System.Net.Http;
+
+namespace Synology.Classes
+{
+    /// <summary>
+    /// </summary>
+    public class SynologyHttpClient : HttpClient
+    {
+        /// <summary>
+        /// </summary>
+        public SynologyHttpClient()
+        {
+        }
+
+        /// <summary>
+        /// </summary>
+        public SynologyHttpClient(HttpMessageHandler handler) : base(handler)
+        {
+        }
+
+        /// <summary>
+        /// </summary>
+        public SynologyHttpClient(HttpMessageHandler handler, bool disposeHandler) : base(handler, disposeHandler)
+        {
+        }
+    }
+}

Synology/Extensions/ServiceCollectionExtension.cs

@@ -21,9 +21,18 @@ public static IServiceCollection AddSynology(this IServiceCollection services, A
         {
             if (configure == null) throw new ArgumentNullException(nameof(configure));
 
+            var defaultHttpClient = new SynologyHttpClient()
+            {
+                DefaultRequestHeaders =
+                {
+                    ExpectContinue = false
+                }
+            };
+
             services.AddOptions();
             services.AddSingleton<ISynologyConnectionSettings, SynologyConnectionSettings>();
             services.AddSingleton<SidContainer, SidContainer>();
+            services.AddSingleton<SynologyHttpClient>(defaultHttpClient);
             services.AddTransient<ISynologyConnection, SynologyConnection>();
 
             configure(new SynologyBuilder(services));

Synology/SynologyConnection.cs

@@ -1,66 +1,63 @@
-using System;
-using System.Net.Http;
-using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging;
+using Synology.Classes;
 using Synology.Interfaces;
+using System;
+using System.Net.Http;
 
 namespace Synology
 {
-	/// <inheritdoc />
-	/// <summary>
-	/// 
-	/// </summary>
-	internal sealed class SynologyConnection : ISynologyConnection
-	{
-		/// <inheritdoc />
-		/// <summary>
-		/// </summary>
-		public ILogger Logger { get; }
-
-		/// <inheritdoc />
-		/// <summary>
-		/// </summary>
-		public ISynologyConnectionSettings Settings { get; }
-
-		/// <inheritdoc />
-		/// <summary>
-		/// </summary>
-		public HttpClient Client { get; }
-
-		/// <inheritdoc />
-		/// <summary>
-		/// </summary>
-		public IServiceProvider ServiceProvider { get; }
-
-		/// <summary>
-		/// 
-		/// </summary>
-		/// <param name="settings"></param>
-		/// <param name="loggerFactory"></param>
-		/// <param name="serviceProvider"></param>
-		public SynologyConnection(ISynologyConnectionSettings settings, ILoggerFactory loggerFactory, IServiceProvider serviceProvider)
-		{
-			Settings = settings;
-			ServiceProvider = serviceProvider;
-			Logger = loggerFactory.CreateLogger<SynologyConnection>();
-
-			Logger.LogDebug($"Creating new connection to {Settings.BaseHost} with{(Settings.Ssl ? "" : "out")} SSL to port {Settings.Port}");
-
-			Client = new HttpClient
-			{
-				BaseAddress = new Uri(Settings.WebApiUrl),
-				DefaultRequestHeaders = {
-					ExpectContinue = false
-				}
-			};
-		}
-
-		/// <inheritdoc />
-		/// <summary>
-		/// </summary>
-		public void Dispose()
-		{
-			Logger.LogDebug("Closing connection");
-			Client?.Dispose();
-		}
-	}
+    /// <inheritdoc />
+    /// <summary>
+    /// 
+    /// </summary>
+    internal sealed class SynologyConnection : ISynologyConnection
+    {
+        /// <inheritdoc />
+        /// <summary>
+        /// </summary>
+        public ILogger Logger { get; }
+
+        /// <inheritdoc />
+        /// <summary>
+        /// </summary>
+        public ISynologyConnectionSettings Settings { get; }
+
+        /// <inheritdoc />
+        /// <summary>
+        /// </summary>
+        public HttpClient Client { get; }
+
+        /// <inheritdoc />
+        /// <summary>
+        /// </summary>
+        public IServiceProvider ServiceProvider { get; }
+
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="settings"></param>
+        /// <param name="loggerFactory"></param>
+        /// <param name="serviceProvider"></param>
+        /// <param name="httpClient"></param>
+        public SynologyConnection(ISynologyConnectionSettings settings, ILoggerFactory loggerFactory, IServiceProvider serviceProvider, SynologyHttpClient httpClient)
+        {
+            Settings = settings;
+            ServiceProvider = serviceProvider;
+            Logger = loggerFactory.CreateLogger<SynologyConnection>();
+
+            Logger.LogDebug($"Creating new connection to {Settings.BaseHost} with{(Settings.Ssl ? "" : "out")} SSL to port {Settings.Port}");
+
+            httpClient.BaseAddress = new Uri(Settings.WebApiUrl);
+            Client = httpClient;
+        }
+
+        /// <inheritdoc />
+        /// <summary>
+        /// </summary>
+        public void Dispose()
+        {
+            Logger.LogDebug("Closing connection");
+            Client?.Dispose();
+        }
+    }
 }