Ignore Xcode dir in coverage reports
Ignore Xcode dir in coverage reports

Summary:
Getting rid of objc files included in test coverage.
Closes https://github.com/Instagram/IGListKit/pull/230

Differential Revision: D4211420

Pulled By: rnystrom

fbshipit-source-id: 451e8eb2fa877afc7121e024811b6d9da47e4a53

charles0126dev/IGListKit,Instagram/IGListKit,zhubofei/IGListKit,zhubofei/IGListKit,charles0126dev/IGListKit,Sherlouk/IGListKit,Sherlouk/IGListKit,Instagram/IGListKit,Instagram/IGListKit,zhubofei/IGListKit,charles0126dev/IGListKit,Instagram/IGListKit,zhubofei/IGListKit,dshahidehpour/IGListKit,dshahidehpour/IGListKit,dshahidehpour/IGListKit,Instagram/IGListKit,zhubofei/IGListKit,Sherlouk/IGListKit