Remove knowledge of fbjs from the packager

Summary:Follow-up to facebook/react-native#5084

This…
- changes all requires within RN to `require('fbjs/lib/…')`
- updates `.flowconfig`
- updates `packager/blacklist.js`
- adapts tests
- removes things from `Libraries/vendor/{core,emitter}` that are also in fbjs
- removes knowledge of `fbjs` from the packager

Closes facebook/react-native#5084

Reviewed By: bestander

Differential Revision: D2926835

fb-gh-sync-id: 2095e22b2f38e032599d1f2601722b3560e8b6e9
shipit-source-id: 2095e22b2f38e032599d1f2601722b3560e8b6e9

Author: davidaurelio

CameraRoll.js

@@ -17,7 +17,7 @@ var RCTCameraRollManager = require('NativeModules').CameraRollManager;
 var createStrictShapeTypeChecker = require('createStrictShapeTypeChecker');
 var deepFreezeAndThrowOnMutationInDev =
   require('deepFreezeAndThrowOnMutationInDev');
-var invariant = require('invariant');
+var invariant = require('fbjs/lib/invariant');
 
 var GROUP_TYPES_OPTIONS = [
   'Album',