Merge pull request #2 from CocoaChina-editors/master

merge update
Merge branch 'master' of https://github.com/CocoaChina-editors/Welcome-to-Swift
Merge pull request #52 from Creolophus/master

Using Swift with Cocoa and Objective-C B.1-1 Getting Started 翻译完毕
Merge branch 'master' of https://github.com/CocoaChina-editors/Welcome-to-Swift
整理md格式

整理md格式
Merge pull request #2 from CocoaChina-editors/master

pr