Bumps lodash.assign to 4.2.0 (reactjs#277)

closes reactjs#238

Author: claydiffrient

package.json

@@ -47,7 +47,7 @@
   "dependencies": {
     "element-class": "^0.2.0",
     "exenv": "1.2.0",
-    "lodash.assign": "^3.2.0"
+    "lodash.assign": "^4.2.0"
   },
   "peerDependencies": {
     "react": "^0.14.0 || ^15.0.0",