Bump to 1.2.0

Summary:
Turns out I published 1.1.0 previously by accident and unpublished /ducks
Closes https://github.com/facebook/react-native/pull/10684

Differential Revision: D4111999

Pulled By: bestander

fbshipit-source-id: a85c8db6e7f48c9e96a649f017d82cbef44c73ae

react-native-cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-native-cli",
-  "version": "1.1.0",
+  "version": "1.2.0",
   "license": "BSD-3-Clause",
   "description": "The React Native CLI tools",
   "main": "index.js",