Use 'fbjs' instead of separate packages

package.json

@@ -16,8 +16,7 @@
     "test:watch": "npm run test:unit -- --no-single-run"
   },
   "dependencies": {
-    "exenv": "^1.2.0",
-    "invariant": "^2.2.0",
+    "fbjs": "^0.7.2",
     "inline-style-prefixer": "^0.6.7",
     "lodash.debounce": "^3.1.1",
     "react-tappable": "^0.7.1",
@@ -28,6 +27,7 @@
     "babel-core": "^6.3.13",
     "babel-eslint": "^4.1.6",
     "babel-loader": "^6.2.0",
+    "babel-plugin-transform-decorators-legacy": "^1.3.4",
     "babel-preset-es2015": "^6.3.13",
     "babel-preset-react": "^6.3.13",
     "babel-preset-stage-1": "^6.3.13",