swift: adding .gitignore (#267)
swift: adding .gitignore (#267)

HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II,HaliteChallenge/Halite-II