updated packages to use react ^16

Author: Alan Hong

package.json

@@ -48,7 +48,7 @@
   "author": "Chi Vinh Le and contributors (https://github.com/wikiwi/react-css-transition/graphs/contributors)",
   "license": "MIT",
   "peerDependencies": {
-    "react": "^15.0.0"
+    "react": "^16.0.0"
   },
   "devDependencies": {
     "@types/chai": "^3.4.34",
@@ -103,9 +103,9 @@
     "postcss-loader": "^1.2.2",
     "postcss-nesting": "^2.3.1",
     "raw-loader": "^0.5.1",
-    "react": "^15.4.2",
+    "react": "^16.8.6",
     "react-addons-test-utils": "^15.4.2",
-    "react-dom": "^15.4.2",
+    "react-dom": "^16.8.6",
     "react-icons": "^2.2.3",
     "react-syntax-highlighter": "^4.0.1",
     "sinon": "^2.0.0-pre.4",