[Fix] re-enable no-confusing-arrow rule, with allowParens option enabled.

Per #752, fixes #791.

packages/eslint-config-airbnb/rules/es6.js

@@ -30,7 +30,9 @@ module.exports = {
     'no-class-assign': 0,
     // disallow arrow functions where they could be confused with comparisons
     // http://eslint.org/docs/rules/no-confusing-arrow
-    'no-confusing-arrow': 0,
+    'no-confusing-arrow': [2, {
+      'allowParens': true,
+    }],
     // disallow modifying variables that are declared using const
     'no-const-assign': 2,
     // disallow symbol constructor