Add root: true to eslint config. (babel/babel-eslint#294)

This prevents taking user's eslint config files that are higher in the
directory structure into consideration.

eslint/babel-eslint-parser/.eslintrc

@@ -1,4 +1,5 @@
 {
+  "root": true,
   "rules": {
     "strict": 0,
     "no-underscore-dangle": 0,
@@ -24,4 +25,4 @@
     "node": true,
     "mocha": true
   }
-}
+}