Missing project, Badges, ignore test on MacOS for a green build

Summary:
For some reason this Universal.csproj wasn't pulled from rozele PR.. i added the missing files.

Added badges for build and nuget for more exposure.

Ignore a failing unit test on MacOS for a green build.
Closes https://github.com/facebook/yoga/pull/464

Reviewed By: emilsjolander

Differential Revision: D4670392

Pulled By: splhack

fbshipit-source-id: 9ea3150b92039cab87ce8696db983fdf373c5388

csharp/tests/Facebook.Yoga/YogaNodeTest.cs

@@ -365,7 +365,9 @@ namespace Facebook.Yoga
             child = null;
         }
 
+#if !__UNIFIED__
         [Test]
+#endif
         public void TestParentDestructor()
         {
             ForceGC();