-Wshadow and warnings as errors for all targets
-Wshadow and warnings as errors for all targets

Summary:
Project settings match internal project gen settings. Was missing from tests.

Issue fixed: #544 #545

- [x] All tests pass. Demo project builds and runs.
- [x] I added tests, an experiment, or detailed why my change isn't tested.
Closes https://github.com/Instagram/IGListKit/pull/549

Differential Revision: D4701754

Pulled By: rnystrom

fbshipit-source-id: f891c1db074a5e54994af3043fdc19c36cbbe371

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