lock eslint version

package.json

@@ -37,7 +37,7 @@
     "cross-port-killer": "^1.0.1",
     "enzyme": "^2.9.1",
     "eslint": "^3.0.0",
-    "eslint-config-airbnb": "latest",
+    "eslint-config-airbnb": "^15.0.0",
     "eslint-plugin-babel": "^4.0.0",
     "eslint-plugin-import": "^2.2.0",
     "eslint-plugin-jsx-a11y": "^5.0.1",