Fix for Issue #1471

This change will allow `GuildAvailable` to fire when the client joins a new guild, as well as properly update `IsConnected`.

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -627,6 +627,10 @@ namespace Discord.WebSocket
                                         var guild = AddGuild(data, State);
                                         if (guild != null)
                                         {
+                                            if (_unavailableGuildCount != 0)
+                                                _unavailableGuildCount--;
+                                                
+                                            await GuildAvailableAsync(guild).ConfigureAwait(false);
                                             await TimedInvokeAsync(_joinedGuildEvent, nameof(JoinedGuild), guild).ConfigureAwait(false);
                                         }
                                         else