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!
```
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
