Changed xcode version to 8.3 in .travis file
Changed xcode version to 8.3 in .travis file

Summary:
Updated osx_image to xcode8.3, close #590

Issue fixed:
- Updated .travis file osx_image to 8.3
- Updated iphonesimulator and tvossimulator.
- Doesn't require tests, as it'll either pass with no changes to the codebase or break CI.

- [x ] All tests pass. Demo project builds and runs.
- [x ] I added tests, an experiment, or detailed why my change isn't tested.
- [x ] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes.
- [x ] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md)
Closes https://github.com/Instagram/IGListKit/pull/594

Differential Revision: D4797499

Pulled By: jessesquires

fbshipit-source-id: a45c6c849564d08ba995ebf97b4ddf9937609d77

zhubofei/IGListKit,Instagram/IGListKit,Instagram/IGListKit,zhubofei/IGListKit,zhubofei/IGListKit,zhubofei/IGListKit,Instagram/IGListKit,Instagram/IGListKit,Instagram/IGListKit,zhubofei/IGListKit