Add proper Upgrade form

Source/LibationAvalonia/Dialogs/UpgradeNotificationDialog.axaml

@@ -0,0 +1,91 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        mc:Ignorable="d" d:DesignWidth="550" d:DesignHeight="450"
+        x:Class="LibationAvalonia.Dialogs.UpgradeNotificationDialog"
+		xmlns:controls="clr-namespace:LibationAvalonia.Controls"
+		MinWidth="500" MinHeight="400"
+		Height="550" Width="450"
+		
+		WindowStartupLocation="CenterOwner"
+        Title="Upgrade Available"
+		Icon="/Assets/libation.ico">
+
+	<Grid  Margin="6" RowDefinitions="Auto,*,Auto">
+		<TextBlock
+			TextWrapping="WrapWithOverflow"
+			FontSize="15"
+			Text="{Binding TopMessage}"
+			IsVisible="{Binding TopMessage, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"/>
+
+		<controls:GroupBox
+			Grid.Row="1"
+			BorderWidth="2"
+			Label="Release Information"
+			Margin="0,10,0,10">
+			
+			<Grid RowDefinitions="*,Auto,Auto">
+
+				<TextBox
+					Grid.Row="0"
+					Margin="0,5,0,10"
+					Grid.ColumnSpan="2"
+					IsReadOnly="true"
+					TextWrapping="WrapWithOverflow"
+					FontSize="12"
+					HorizontalAlignment="Stretch"
+					Text="{Binding ReleaseNotes}" />
+				
+				<TextBlock						
+					Grid.Row="1"
+					VerticalAlignment="Bottom"
+					Text="Download Release:" />
+
+				<controls:LinkLabel
+					Grid.Row="1"
+					Margin="0,0,0,10"
+					VerticalAlignment="Center"
+					HorizontalAlignment="Right"
+					Text="View the source code on GitHub"
+					Tapped="Github_Tapped" />
+
+				<controls:LinkLabel
+					Grid.Row="2"
+					Margin="0,0,0,10"
+					VerticalAlignment="Center"
+					Text="{Binding DownloadLinkText}"
+					Tapped="Download_Tapped" />
+
+				<controls:LinkLabel
+					Grid.Row="2"
+					VerticalAlignment="Center"
+					HorizontalAlignment="Right"
+					Text="Go to Libation's website"
+					Tapped="Website_Tapped" />
+
+			</Grid>
+
+		</controls:GroupBox>
+		<Grid
+			Grid.Row="3"
+			ColumnDefinitions="*,Auto">
+
+			<Button
+				Grid.Column="0"
+				HorizontalAlignment="Left"
+				Content="Don't remind me&#x0a;about this release"
+				Click="DontRemind_Click" />
+			<Button
+				Grid.Column="1"
+				TabIndex="0"
+				FontSize="16"
+				Padding="30,0,30,0"
+				VerticalAlignment="Stretch"
+				HorizontalAlignment="Right"
+				VerticalContentAlignment="Center"
+				Content="{Binding OkText}"
+				Click="OK_Click" />
+		</Grid>
+	</Grid>
+</Window>