Summary:
`File not found` occurs in AppCode.
`sourceTree` of `RCTActionSheet.xcodeproj` is `<absolute>`. Because path is `../../Libraries/ActionSheetIOS/RCTActionSheet.xcodeproj`, that sourceTree is wrong.
Closes#338
Closes https://github.com/facebook/react-native/pull/344
Github Author: Leonardo YongUk Kim <dalinaum@gmail.com>
Test Plan: Imported from GitHub, without a `Test Plan:` line.