Summary:
This supersedes #309 and #305.
This is still a **work-in-progress.**
**TODO**
- [x] Create Xcode project that builds an iOS framework
- [x] Fix failing tests on Xcode
- [ ] Make `pod lib lint` pass and make sure YogaKit can be included using CocoaPods
- [ ] Add `pod lib lint` to .travis.yml
- [x] Migrate to travis osx image with Xcode 8.2
**FOLLOW-UP**
- [ ] Make YogaKitSample use framework built by new Xcode project.
- [ ] Make Travis to upload prebuilt versions of the framework. More [here](https://github.com/Carthage/Carthage#use-travis-ci-to-upload-your-tagged-prebuild-frameworks)
- [ ] Upgrade github/jekyll docs about installation using Cocoapods/Carthage
Closes https://github.com/facebook/yoga/pull/352
Reviewed By: emilsjolander
Differential Revision: D4471950
Pulled By: dshahidehpour
fbshipit-source-id: 8f30c69f9a487b26aa2e5f3b66841334b01b0ab1
