Add Xamarin Android support

Summary:
Adds a Xamarin Android support for Yoga and respective tests. Closes #276 with this PR all Xamarin platforms will be covered

Need to figure a better strategy for the build names for buck with splhack .

It's failing 3 tests related with YogaNode and the GC :) classic!

![screenshot_1484353863](https://cloud.githubusercontent.com/assets/1235097/21950981/61020212-d9f8-11e6-80e1-185bd1707f9a.png)

```
Facebook.Yoga.Android.Tests.dll : 660.87 ms
 : 678.788 ms
Tests run: 130, Passed: 127, Failed: 3, Skipped: 0, Inconclusive: 0
```
Closes https://github.com/facebook/yoga/pull/340

Reviewed By: emilsjolander

Differential Revision: D4475370

Pulled By: splhack

fbshipit-source-id: f050f10415e68e9808f629b843682b0f87cca065

csharp/Android/Facebook.Yoga.Android.Tests/Facebook.Yoga.Android.Tests.csproj

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <ProjectGuid>{2021459E-8FB1-44A4-89F1-E291769CD2C6}</ProjectGuid>
+    <ProjectTypeGuids>{EFBA0AD7-5A72-4C68-AF49-83D382785DCF};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <OutputType>Library</OutputType>
+    <RootNamespace>Facebook.Yoga.Android.Tests</RootNamespace>
+    <AssemblyName>Facebook.Yoga.Android.Tests</AssemblyName>
+    <TargetFrameworkVersion>v7.0</TargetFrameworkVersion>
+    <AndroidApplication>True</AndroidApplication>
+    <AndroidResgenFile>Resources\Resource.designer.cs</AndroidResgenFile>
+    <AndroidResgenClass>Resource</AndroidResgenClass>
+    <MonoAndroidResourcePrefix>Resources</MonoAndroidResourcePrefix>
+    <MonoAndroidAssetsPrefix>Assets</MonoAndroidAssetsPrefix>
+    <AndroidUseLatestPlatformSdk>true</AndroidUseLatestPlatformSdk>
+    <AndroidManifest>Properties\AndroidManifest.xml</AndroidManifest>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>DEBUG;</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <AndroidLinkMode>None</AndroidLinkMode>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <AndroidManagedSymbols>true</AndroidManagedSymbols>
+    <AndroidUseSharedRuntime>false</AndroidUseSharedRuntime>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="System" />
+    <Reference Include="System.Xml" />
+    <Reference Include="System.Core" />
+    <Reference Include="Mono.Android" />
+    <Reference Include="Xamarin.Android.NUnitLite" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="MainActivity.cs" />
+    <Compile Include="Resources\Resource.designer.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="Properties\AndroidManifest.xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\Facebook.Yoga.Android\Facebook.Yoga.Android.csproj">
+      <Project>{EDF7CF8B-5640-4E1D-A2C7-E4BC8BE44363}</Project>
+      <Name>Facebook.Yoga.Android</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="..\..\tests\Facebook.Yoga\Facebook.Yoga.Shared.Tests.projitems" Label="Shared" Condition="Exists('..\..\tests\Facebook.Yoga\Facebook.Yoga.Shared.Tests.projitems')" />
+  <Import Project="$(MSBuildExtensionsPath)\Xamarin\Android\Xamarin.Android.CSharp.targets" />
+</Project>

csharp/Android/Facebook.Yoga.Android.Tests/MainActivity.cs

@@ -0,0 +1,25 @@
+/**
+ * Copyright 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the license found in the
+ * LICENSE-examples file in the root directory of this source tree.
+ */
+
+using System.Reflection;
+using Android.App;
+using Android.OS;
+using Xamarin.Android.NUnitLite;
+
+namespace Facebook.Yoga.Android.Tests
+{
+	[Activity(Label = "Facebook.Yoga.Android.Tests", MainLauncher = true)]
+	public class MainActivity : TestSuiteActivity
+	{
+		protected override void OnCreate(Bundle bundle)
+		{
+			AddTest(Assembly.GetExecutingAssembly());
+			base.OnCreate(bundle);
+		}
+	}
+}

csharp/Android/Facebook.Yoga.Android.Tests/Properties/AndroidManifest.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    android:versionCode="1"
+    android:versionName="1.0"
+    package="Facebook.Yoga.Android.Tests">
+
+    <uses-sdk
+        android:minSdkVersion="19" />
+
+    <application
+        android:label="Facebook.Yoga.Android.Tests">
+    </application>
+
+</manifest>