chore(project): simplify .babelrc

Author: nikku

.babelrc

@@ -1,19 +1,8 @@
 {
   "presets": [
-    "stage-0",
-    "stage-1",
-    "stage-2",
-    [
-      "env",
-      {
-        "modules": false,
-        "targets": {
-          "node": "4.8",
-          "browsers": ["last 2 versions"],
-          "ie": 8
-        }
-      }
-    ]
+    "env"
   ],
-  "plugins": ["transform-object-rest-spread"]
+  "plugins": [
+    "transform-object-rest-spread"
+  ]
 }