Update proposal stages used

Author: jakezatecky

.babelrc

@@ -1,3 +1,3 @@
 {
-  "presets": ["react", "es2015", "stage-0"]
+  "presets": ["react", "es2015", "stage-2"]
 }

package.json

@@ -31,7 +31,7 @@
     "babel-loader": "^6.2.4",
     "babel-preset-es2015": "^6.13.2",
     "babel-preset-react": "^6.11.1",
-    "babel-preset-stage-0": "^6.5.0",
+    "babel-preset-stage-2": "^6.5.0",
     "browser-sync": "^2.18.6",
     "chai": "^3.5.0",
     "enzyme": "^2.7.1",