Moving react as a peerDependency

- Currently we have react 15.x.x as a hard dependency in react-json-schema.
- If consumers of react-json-schema are still on 0.14.x, this means we will now have two versions of react in our final bundle.
- To avoid this set react 15.x.x as a peer dependency. This way applications consuming react-json-schema can gradually migrate to react 15.x.x and still use react-json-schema with no sideeffects on bundle size

Author: Nikhilesh Katakam

package.json

@@ -38,7 +38,7 @@
     "lib",
     "dist"
   ],
-  "dependencies": {
+  "peerDependencies": {
     "react": "^15.3.0"
   },
   "devDependencies": {
@@ -64,6 +64,7 @@
     "react-dom": "^15.3.0",
     "uglify-js": "^2.7.0",
     "webpack": "^1.12.2",
-    "webpack-dev-server": "^1.12.0"
+    "webpack-dev-server": "^1.12.0",
+    "react": "^15.3.0"
   }
 }