Xcode8_swift3.0

[kameike]

Update for Swift3.0 in Xcode8

• this branch checked out from #21(Xcode8_swift2.3)
• Every test in every device( iOS, appleTV, watchOS, Mac) is passed
• Almost change is by Xcode [Edit -> Convert]
• I change some sowing below

Place where I changed

• add @discardableResult to seems need to avoid warning f195fed
• make test pass cc960dd

[sidestepism]

@nori0620 Do you have a plan to merge this PR and #21 ?