Merge pull request react-bootstrap#1470 from taion/dev-expression

Use dev-expression Babel plugin

Author: taion

.babelrc

@@ -1,5 +1,6 @@
 {
   "stage": 1,
   "optional": ["runtime"],
-  "loose": ["all"]
+  "loose": ["all"],
+  "plugins": ["dev-expression"]
 }

package.json

@@ -48,6 +48,7 @@
     "babel-core": "^5.8.25",
     "babel-eslint": "^4.1.3",
     "babel-loader": "^5.3.2",
+    "babel-plugin-dev-expression": "^0.1.0",
     "bootstrap": "^3.3.5",
     "brfs": "^1.4.1",
     "chai": "^3.3.0",