Change reference to use v13 Xamarin component as per @slodge

.gitignore

@@ -25,4 +25,5 @@ version-bump.patch
 ReactiveUI.Events/Events.cs
 ReactiveUI.Events/Events_*.cs
 
-packages
+packages
+Components

ReactiveUI.Platforms/ReactiveUI.Android.csproj

@@ -42,7 +42,6 @@
     <DocumentationFile>bin\Release\Monoandroid\ReactiveUI.Android.XML</DocumentationFile>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="Mono.Android.Support.v4" />
     <Reference Include="System" />
     <Reference Include="System.Xml" />
     <Reference Include="System.Core" />
@@ -66,6 +65,9 @@
     <Reference Include="Splat">
       <HintPath>..\ext\monodroid\Splat.dll</HintPath>
     </Reference>
+    <Reference Include="Xamarin.Android.Support.v13">
+      <HintPath>..\Components\xamandroidsupportv13-18-13.18.1\lib\android\Xamarin.Android.Support.v13.dll</HintPath>
+    </Reference>
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath)\Novell\Novell.MonoDroid.CSharp.targets" />
   <ItemGroup>
@@ -102,4 +104,10 @@
       <Name>ReactiveUI</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <XamarinComponentReference Include="xamandroidsupportv13-18">
+      <Visible>False</Visible>
+      <Version>13.18.1</Version>
+    </XamarinComponentReference>
+  </ItemGroup>
 </Project>