Summary:
This PR updates the openssl dependency with OpenSSL-Universal, which ships a fat-binary of libssl and libcrypto with all the architecture.
This PR also updates the travis to cache cocoapods checkout directory.
## Changelog
Updated Flipper-Folly deps
Pull Request resolved: https://github.com/facebook/flipper/pull/577
Test Plan: CI
Reviewed By: jknoxville
Differential Revision: D17877304
Pulled By: priteshrnandgaonkar
fbshipit-source-id: 9d13308108b6665d4bf5dd6145fcaafa2a2a8a13
ab121f9d96