Update .travis.yml
Update .travis.yml

The build is failing because travis fails to build yoga-layout from react-sketchapp, which is a dependency of this project.
The way react-sketchapp builds is they do it osx.
lelandrichardson/react-primitives,lelandrichardson/react-primitives,lelandrichardson/react-primitives,lelandrichardson/react-primitives