Call RCTInitializing initialize on NativeModules
Call RCTInitializing initialize on NativeModules

Summary:
After D28435078, NativeModules can conform to the RCTInitializing protocol, and implement the `-(void)initialize` method. This diff makes the NativeModule system execute the module's initialize method after the infra is done setting it up.

Changelog: [Internal]

Reviewed By: fkgozali

Differential Revision: D28435430

fbshipit-source-id: 1ce00c3fb3c63b024d7e24895ff96c541a6fa654

janicduplessis/react-native,facebook/react-native,facebook/react-native,janicduplessis/react-native,pandiaraj44/react-native,javache/react-native,pandiaraj44/react-native,pandiaraj44/react-native,janicduplessis/react-native,javache/react-native,pandiaraj44/react-native,pandiaraj44/react-native,pandiaraj44/react-native,javache/react-native,facebook/react-native,pandiaraj44/react-native,javache/react-native,javache/react-native,facebook/react-native,janicduplessis/react-native,javache/react-native,facebook/react-native,janicduplessis/react-native,janicduplessis/react-native,pandiaraj44/react-native,javache/react-native,javache/react-native,facebook/react-native,facebook/react-native,facebook/react-native,facebook/react-native,javache/react-native,janicduplessis/react-native,janicduplessis/react-native