Adds builders for Thumbnail and Image embeds, and adds json model for Video and Image embeds.

src/Discord.Net.Rest/Entities/Messages/Embed.cs

@@ -14,6 +14,8 @@ namespace Discord
         public string Title { get; }
         public string Type { get; }
         public Color? Color { get; }
+        public EmbedImage? Image { get; }
+        public EmbedVideo? Video { get; }
         public EmbedAuthor? Author { get; }
         public EmbedFooter? Footer { get; }
         public EmbedProvider? Provider { get; }
@@ -25,6 +27,8 @@ namespace Discord
             string description, 
             string url, 
             Color? color, 
+            EmbedImage? image,
+            EmbedVideo? video,
             EmbedAuthor? author, 
             EmbedFooter? footer, 
             EmbedProvider? provider, 
@@ -36,6 +40,8 @@ namespace Discord
             Description = description;
             Url = url;
             Color = color;
+            Image = image;
+            Video = video;
             Author = author;
             Footer = footer;
             Provider = provider;
@@ -46,6 +52,8 @@ namespace Discord
         {
             return new Embed(model.Type, model.Title, model.Description, model.Url,
                 model.Color.HasValue ? new Color(model.Color.Value) : (Color?)null,
+                model.Image.IsSpecified ? EmbedImage.Create(model.Image.Value) : (EmbedImage?)null,
+                model.Video.IsSpecified ? EmbedVideo.Create(model.Video.Value) : (EmbedVideo?)null,
                 model.Author.IsSpecified ? EmbedAuthor.Create(model.Author.Value) : (EmbedAuthor?)null,
                 model.Footer.IsSpecified ? EmbedFooter.Create(model.Footer.Value) : (EmbedFooter?)null,
                 model.Provider.IsSpecified ? EmbedProvider.Create(model.Provider.Value) : (EmbedProvider?)null,