Enable TreatWarningsAsErrors for MediaBrowser.Common and Emby.Photos

Adds `#pragma warning disable CS1591` to all files in
MediaBrowser.Common containing undocumented members.

MediaBrowser.Common/Configuration/ConfigurationUpdateEventArgs.cs

@@ -1,3 +1,5 @@
+#pragma warning disable CS1591
+
 using System;
 
 namespace MediaBrowser.Common.Configuration
@@ -9,6 +11,7 @@ namespace MediaBrowser.Common.Configuration
         /// </summary>
         /// <value>The key.</value>
         public string Key { get; set; }
+
         /// <summary>
         /// Gets or sets the new configuration.
         /// </summary>